diff --git a/common/components/protocols.js b/common/components/protocols.js
index a3c87ae5..f37a0ebf 100644
--- a/common/components/protocols.js
+++ b/common/components/protocols.js
@@ -111,6 +111,7 @@ Dactyl.prototype = {
             for (let [k, v] in Iterator(obj[prop] || {}))
                 this[prop][k] = v;
         }
+        this.initialized = true;
     },
 
     scheme: "dactyl",
diff --git a/common/content/commandline.js b/common/content/commandline.js
index b9e2147d..cd7f8c22 100644
--- a/common/content/commandline.js
+++ b/common/content/commandline.js
@@ -940,14 +940,18 @@ const CommandLine = Module("commandline", {
                 dactyl.open(event.target.href, where);
             }
 
+            let command = event.originalTarget.getAttributeNS(NS.uri, "command");
+            if (command && dactyl.commands[command]) {
+                return dactyl.withSavedValues(["forceNewTab"], function () {
+                    dactyl.forceNewTab = event.ctrlKey || event.shiftKey || event.button == 1;
+                    dactyl.commands[command](event);
+                });
+            }
+
             switch (key) {
             case "<LeftMouse>":
                 event.preventDefault();
-                let command = event.originalTarget.getAttributeNS(NS.uri, "command");
-                if (command && dactyl.commands[command])
-                    return dactyl.commands[command](event);
-                else
-                    openLink(dactyl.CURRENT_TAB);
+                openLink(dactyl.CURRENT_TAB);
                 return false;
             case "<MiddleMouse>":
             case "<C-LeftMouse>":
@@ -1708,7 +1712,7 @@ const CommandLine = Module("commandline", {
             { validator: function (value) value >= 1 });
 
         options.add(["messages", "msgs"],
-            "Number of messages to store in the :message history",
+            "Number of messages to store in the :messages history",
             "number", 100,
             { validator: function (value) value >= 0 });
 
diff --git a/common/content/commands.js b/common/content/commands.js
index 46f9a4fb..5c16bc8e 100644
--- a/common/content/commands.js
+++ b/common/content/commands.js
@@ -1395,6 +1395,15 @@ const Commands = Module("commands", {
                 completer: function (context) completion.userCommand(context)
             });
 
+        dactyl.addUsageCommand({
+            name: ["listc[ommands]", "lc"],
+            description: "List all Ex commands along with their short descriptions",
+            iterate: function (args) commands,
+            format: {
+                description: function (cmd) template.linkifyHelp(cmd.description + (cmd.replacementText ? ": " + cmd.action : ""))
+            }
+        });
+
         function checkStack(cmd) {
             util.assert(io.sourcing && io.sourcing.stack &&
                         io.sourcing.stack[cmd] && io.sourcing.stack[cmd].length,
@@ -1454,13 +1463,14 @@ const Commands = Module("commands", {
         commands.add(["y[ank]"],
             "Yanks the output of the given command to the clipboard",
             function (args) {
-                let res = commandline.withOutputToString(commands.execute, commands, args[0]);
+                let cmd = /^:/.test(args[0]) ? args[0] : ":echo " + args[0];
+                let res = commandline.withOutputToString(commands.execute, commands, cmd);
                 dactyl.clipboardWrite(res);
                 let lines = res.split("\n").length;
                 dactyl.echomsg("Yanked " + lines + " line" + (lines == 1 ? "" : "s"));
             },
             {
-                completer: function (context) completion.ex(context),
+                completer: function (context) completion[/^:/.test(context.filter) ? "ex" : "javascript"](context),
                 literal: 0
             });
     },
diff --git a/common/content/dactyl.js b/common/content/dactyl.js
index 84731c65..bf2b0bdc 100644
--- a/common/content/dactyl.js
+++ b/common/content/dactyl.js
@@ -48,6 +48,10 @@ const Dactyl = Module("dactyl", {
         this.commands = {};
         this.modules = modules;
         this.observers = {};
+
+        this.commands["dactyl.help"] = function (event) {
+            dactyl.help(event.originalTarget.textContent);
+        };
     },
 
     /** @property {string} The name of the current user profile. */
@@ -139,6 +143,35 @@ const Dactyl = Module("dactyl", {
             });
     },
 
+    addUsageCommand: function (params) {
+        commands.add(params.name, params.description,
+            function (args) {
+                let results = array(params.iterate(args))
+                    .sort(function (a, b) String.localeCompare(a.name, b.name));
+                if (args.length)
+                    results = results.filter(function (item) args.map(String.toLowerCase)
+                        .every(function (arg) (item.name + item.description).toLowerCase().indexOf(arg) >= 0));
+                commandline.commandOutput(
+                    template.usage(results, params.format));
+            },
+            {
+                argCount: "*",
+                completer: function (context, args) {
+                    context.keys.text = util.identity;
+                    context.keys.description = function () seen[this.text] + " matching items";
+                    let seen = {};
+                    context.completions = array(item.description.toLowerCase().split(/[()\s]+/)
+                                                for (item in params.iterate(args)))
+                        .flatten().filter(function (w) /^\w[\w-_']+$/.test(w))
+                        .map(function (k) {
+                            seen[k] = (seen[k] || 0) + 1;
+                            return k;
+                        }).uniq()
+                },
+                options: params.options || []
+            });
+    },
+
     /**
      * Triggers the application bell to notify the user of an error. The
      * bell may be either audible or visual depending on the value of the
@@ -257,8 +290,7 @@ const Dactyl = Module("dactyl", {
         if (typeof str == "object" && "echoerr" in str)
             str = str.echoerr;
         else if (isinstance(str, ["Error"]))
-            str = str.fileName.replace(/^.*? -> /, "")
-                + ":" + str.lineNumber + ": " + str;
+            str = <>{str.fileName.replace(/^.*? -> /, "")}: {str.lineNumber}: {str}</>;
 
         if (options["errorbells"])
             dactyl.beep();
@@ -1044,7 +1076,7 @@ const Dactyl = Module("dactyl", {
     reportError: function reportError(error, echo) {
         if (error instanceof FailedAssertion || error.message === "Interrupted") {
             if (error.message)
-                dactyl.echoerr(error.message);
+                dactyl.echoerr(template.linkifyHelp(error.message));
             else
                 dactyl.beep();
             return;
@@ -1935,7 +1967,6 @@ const Dactyl = Module("dactyl", {
                 argCount: "0",
                 bang: true
             });
-
     },
 
     completion: function () {
diff --git a/common/content/mappings.js b/common/content/mappings.js
index 08c71404..db256085 100644
--- a/common/content/mappings.js
+++ b/common/content/mappings.js
@@ -185,16 +185,17 @@ const Mappings = Module("mappings", {
                     some(function (m) m.rhs && m.rhs === map.rhs && m.name === map.name))))
     },
 
-    // NOTE: just normal mode for now
-    /** @property {Iterator(Map)} @private */
-    __iterator__: function () {
-        let mode = modes.NORMAL;
+    iterate: function (mode) {
         let seen = {};
         for (let map in iterAll(values(this._user[mode]), values(this._main[mode])))
             if (!set.add(seen, map.name))
                 yield map;
     },
 
+    // NOTE: just normal mode for now
+    /** @property {Iterator(Map)} */
+    __iterator__: function () this.iterate(modes.NORMAL),
+
     // used by :mkpentadactylrc to save mappings
     /**
      * Returns a user-defined mappings iterator for the specified *mode*.
@@ -381,19 +382,6 @@ const Mappings = Module("mappings", {
                 }
             }
 
-            function findMode(name) {
-                for (let mode in modes.mainModes)
-                    if (name == mode || name == mode.char || String.toLowerCase(name).replace(/-/g, "_") == mode.name.toLowerCase())
-                        return mode.mask;
-                return null;
-            }
-            function uniqueModes(modes) {
-                modes = modes.map(modules.modes.closure.getMode);
-                let chars = [k for ([k, v] in Iterator(modules.modes.modeChars))
-                             if (v.every(function (mode) modes.indexOf(mode) >= 0))];
-                return array.uniq(modes.filter(function (m) chars.indexOf(m.char) < 0).concat(chars));
-            }
-
             const opts = {
                     completer: function (context, args) {
                         if (args.length == 1)
@@ -511,8 +499,66 @@ const Mappings = Module("mappings", {
                 });
         }
 
+        function findMode(name) {
+            for (let mode in modes.mainModes)
+                if (name == mode || name == mode.char || String.toLowerCase(name).replace(/-/g, "_") == mode.name.toLowerCase())
+                    return mode.mask;
+            return null;
+        }
+        function uniqueModes(modes) {
+            modes = modes.map(modules.modes.closure.getMode);
+            let chars = [k for ([k, v] in Iterator(modules.modes.modeChars))
+                         if (v.every(function (mode) modes.indexOf(mode) >= 0))];
+            return array.uniq(modes.filter(function (m) chars.indexOf(m.char) < 0).concat(chars));
+        }
+
         addMapCommands("", [modes.NORMAL, modes.VISUAL], "");
 
+        let args = {
+            getMode: function (args) findMode(args["-mode"]),
+            iterate: function (args) {
+                for (let map in mappings.iterate(this.getMode(args)))
+                    for (let name in values(map.names))
+                        yield { name: name, __proto__: map };
+            },
+            format: {
+                description: function (map) (XML.ignoreWhitespace = false, XML.prettyPrinting = false, <>
+                        {options.get("passkeys").has(map.name)
+                            ? <span highlight="URLExtra">(passed by {template.helpLink("'passkeys'")})</span>
+                            : <></>}
+                        {template.linkifyHelp(map.description + (map.rhs ? ": " + map.rhs : ""))}
+                </>)
+            }
+        }
+
+        dactyl.addUsageCommand({
+            __proto__: args,
+            name: ["listk[eys]", "lk"],
+            description: "List all mappings along with their short descriptions",
+            options: [
+                {
+                    names: ["-mode", "-m"],
+                    type: CommandOption.STRING,
+                    description: "The mode for which to list mappings",
+                    default: "n",
+                    completer: function () [[array.compact([mode.name.toLowerCase().replace(/_/g, "-"), mode.char]), mode.disp]
+                                            for (mode in modes.mainModes)],
+                    validator: function (m) findMode(m)
+                }
+            ]
+        });
+
+        forEach(modes.mainModes, function (mode) {
+            if (mode.char && !commands.get(mode.char + "listkeys", true))
+                dactyl.addUsageCommand({
+                    __proto__: args,
+                    name: [mode.char + "listk[eys]", mode.char + "lk"],
+                    description: "List all " + mode.name + " mode mappings along with their short descriptions",
+                    getMode: function (args) mode,
+                    options: []
+                });
+        });
+
         for (let mode in modes.mainModes)
             if (mode.char && !commands.get(mode.char + "map", true))
                 addMapCommands(mode.char,
diff --git a/common/content/options.js b/common/content/options.js
index 99e6d51f..5454ec62 100644
--- a/common/content/options.js
+++ b/common/content/options.js
@@ -817,6 +817,36 @@ const Options = Module("options", {
 }, {
 }, {
     commands: function () {
+        let args = {
+            getMode: function (args) findMode(args["-mode"]),
+            iterate: function (args) {
+                for (let map in mappings.iterate(this.getMode(args)))
+                    for (let name in values(map.names))
+                        yield { name: name, __proto__: map };
+            },
+            format: {
+                description: function (map) (XML.ignoreWhitespace = false, XML.prettyPrinting = false, <>
+                        {options.get("passkeys").has(map.name)
+                            ? <span highlight="URLExtra">(passed by {template.helpLink("'passkeys'")})</span>
+                            : <></>}
+                        {template.linkifyHelp(map.description)}
+                </>)
+            }
+        }
+
+        dactyl.addUsageCommand({
+            name: ["listo[ptions]", "lo"],
+            description: "List all options along with their short descriptions",
+            iterate: function (args) options,
+            format: {
+                description: function (opt) (XML.ignoreWhitespace = false, XML.prettyPrinting = false, <>
+                        {opt.scope == Option.SCOPE_LOCAL
+                            ? <span highlight="URLExtra">(buffer local)</span> : ""}
+                        {template.linkifyHelp(opt.description)}
+                </>)
+            }
+        });
+
         function setAction(args, modifiers) {
             let bang = args.bang;
             if (!args.length)
diff --git a/common/locale/en-US/various.xml b/common/locale/en-US/various.xml
index db65a99e..b45202ee 100644
--- a/common/locale/en-US/various.xml
+++ b/common/locale/en-US/various.xml
@@ -113,9 +113,12 @@
 
 <item>
     <tags>:yank :y</tags>
-    <spec>:y[ank] <a>cmd</a></spec>
+    <spec>:y[ank] :<a>cmd</a></spec>
+    <spec>:y[ank] <a>js</a></spec>
     <description>
-        <p>Yanks the output of the given command to the clipboard.</p>
+        <p>
+            Yanks the output of the given Ex command <a>cmd</a> or JavaScript <a>js</a> to the clipboard.
+        </p>
     </description>
 </item>
 
diff --git a/common/modules/prefs.jsm b/common/modules/prefs.jsm
index 8c852395..d5c935e3 100644
--- a/common/modules/prefs.jsm
+++ b/common/modules/prefs.jsm
@@ -131,7 +131,7 @@ const Prefs = Module("prefs", XPCOM([Ci.nsIObserver, Ci.nsISupportsWeakReference
         if (saved == null && curval != defval || curval != saved) {
             let msg = "Warning: setting preference " + name + ", but it's changed from its default value.";
             if (message)
-                msg += " " + message;
+                msg = template.linkifyHelp(msg + " " + message);
             util.dactyl.echomsg(msg);
         }
     },
diff --git a/common/modules/template.jsm b/common/modules/template.jsm
index 15f31b9b..b0437aa9 100644
--- a/common/modules/template.jsm
+++ b/common/modules/template.jsm
@@ -7,7 +7,8 @@
 Components.utils.import("resource://dactyl/base.jsm");
 defineModule("template", {
     exports: ["Template", "template"],
-    require: ["util"]
+    require: ["util"],
+    use: ["services"]
 });
 
 default xml namespace = XHTML;
@@ -78,6 +79,16 @@ const Template = Module("Template", {
         // </e4x>
     },
 
+    helpLink: function (topic, type) {
+        if (services["dactyl:"].initialized && !set.has(services["dactyl:"].HELP_TAGS, topic))
+            return <>{topic}</>;
+
+        XML.ignoreWhitespace = false; XML.prettyPrinting = false;
+        type = type || /^'.*'$/.test(topic) ? "HelpOpt" :
+                       /^:\w/.test(topic)   ? "HelpEx"  : "HelpKey";
+        return <a highlight={type} href={"dactyl://help-tag/" + topic} dactyl:command="dactyl.help" xmlns:dactyl={NS}>{topic}</a>
+    },
+
     // if "processStrings" is true, any passed strings will be surrounded by " and
     // any line breaks are displayed as \n
     highlight: function highlight(arg, processStrings, clip) {
@@ -199,6 +210,21 @@ const Template = Module("Template", {
         // </e4x>
     },
 
+    linkifyHelp: function linkifyHelp(str) {
+        util.dactyl.initHelp();
+
+        let re = util.regexp(<![CDATA[
+            ([/\s]|^)
+            ( '[\w-]+' | :(?:[\w-]+|!) | (?:._)?<[\w-]+> )
+            (?=[[!,;./\s]|$)
+        ]]>, "g");
+        return this.highlightSubstrings(str, (function () {
+            let res;
+            while ((res = re.exec(str)) && res[2].length)
+                yield [res.index + res[1].length, res[2].length];
+        })(), template.helpLink);
+    },
+
     options: function options(title, opts) {
         XML.ignoreWhitespace = false; XML.prettyPrinting = false;
         // <e4x>
@@ -285,8 +311,9 @@ const Template = Module("Template", {
         // </e4x>
     },
 
-    usage: function usage(iter) {
+    usage: function usage(iter, format) {
         XML.ignoreWhitespace = false; XML.prettyPrinting = false;
+        let desc = format && format.description || function (item) template.linkifyHelp(item.description);
         // <e4x>
         return <table>
             {
@@ -298,7 +325,7 @@ const Template = Module("Template", {
                                 <span highlight="Title">{name}</span> + <> </> +
                                 <span highlight="LineInfo">Defined at {template.sourceLink(frame)}</span>
                     }</td>
-                    <td>{item.description}</td>
+                    <td>{desc(item)}</td>
                 </tr>)
             }
             </table>;
diff --git a/common/modules/util.jsm b/common/modules/util.jsm
index 0e8c7734..2f3372f8 100644
--- a/common/modules/util.jsm
+++ b/common/modules/util.jsm
@@ -30,7 +30,7 @@ memoize(this, "Commands", function () {
 
 const FailedAssertion = Class("FailedAssertion", Error, {
     init: function (message) {
-        this.message = message;
+        update(this, Error(message))
     }
 });
 
@@ -102,7 +102,7 @@ const Util = Module("Util", XPCOM([Ci.nsIObserver, Ci.nsISupportsWeakReference])
      */
     assert: function (condition, message) {
         if (!condition)
-            throw new FailedAssertion(message);
+            throw FailedAssertion(message);
     },
 
     get chromePackages() {
diff --git a/common/skin/dactyl.css b/common/skin/dactyl.css
index ea5d71e8..5e90659c 100644
--- a/common/skin/dactyl.css
+++ b/common/skin/dactyl.css
@@ -76,6 +76,14 @@
 
 }
 
+@-moz-document
+    url-prefix(chrome://dactyl/) {
+
+*:-moz-any-link:hover {
+    text-decoration: underline;
+}
+}
+
 /* Applied to completion buffer, MOW, browser window */
 @-moz-document
     url-prefix(chrome://) {