Saves/accesses your command history.

command-history.ubiq.js

const Name = 'command-history',
PHistory = 'extensions.ubiquity.history.',
PCache = PHistory +'cache',
PCount = PHistory +'count',
Sep = '\t', InitCount = 40, {prefs} = Application;
CmdUtils.CreateCommand({
  name: Name,
  icon: 'chrome://ubiquity/skin/icons/favicon.ico',
  takes: {regex: {_name: '/re/i', suggest: function(txt, htm, cb, sx){
    if(sx) return [];
    try { var re = RegExp(txt, 'i') } catch(_){ re = /^/ }
    return [{text: txt, data: re, summary: re}];
  }}},
  description: 'Accesses your command history.',
  help: ''+<ul style="list-style-image:none">
    <li>Use accesskey or click to reclaim a command.</li>
    <li>Type <abbr title="Regular Expression">regex</abbr>
      to filter commands.</li>
    <li>Execute to delete all matched commands from history.</li>
    <li>Create or edit <a href="about:config"><code>{PCount}</code></a> to
      set maximum number of commands stored.
      (defaults to {InitCount})</li></ul>,
  execute: function({data}){
    if(!data) return this._show('Type ".*" to delete all.');
    prefs.setValue(PCache, this._find(data, true).join(Sep));
    this._show('Matched commands deleted.');
  },
  preview: function(pbl, {data}){
    var ol = this._find(data).reduce(function(ol, c, i){
      var k = i < 30 ? String.fromCharCode(i + 65) : i < 40 ? i - 30 : '-';
      ol.* += (<li><label for={i}><button id={i} accesskey={k} value={c}
               >{k}</button><code>{c}</code></label></li>);
      return ol;
    }, <ol class={Name}></ol>);
    if(!('li' in ol)){ pbl.innerHTML = this.description + this.help; return }
    pbl.innerHTML = this._style + ol;
    jQuery('button', pbl).each(function(){
       this.addEventListener('focus', function(e){
         var {gUbiquity} = context.chromeWindow;
         gUbiquity.__textBox.value = this.value;
         gUbiquity.__processInput();
         e.preventDefault(), e.stopPropagation();
       }, true) });
  },
  previewDelay: 222,
  _show: function(text){
    displayMessage({icon: this.icon, title: this.name, text: text});
  },
  _find: function(re, ex){
    var ls = prefs.getValue(PCache, '').split(Sep);
    return re ? ls.filter(function(cmd) ex ^ (cmd && re.test(cmd))) : ls;
  },
  _style: <style>{<![CDATA[
    @{margin:0; padding:2px}
    @li {list-style-type:none}
    @button {padding:0; border-width:1px;
      font:bold 108% "Consolas", monospace}
    ]]>.toString().replace(/@/g, '.'+ Name +' ')}</style>,
  author: 'satyr'.link('http://d.hatena.ne.jp/murky-satyr'), license: 'MIT',
});
function startup_commandHistory(){{}
function setup(U){
  U.__msgPanel.addEventListener('popuphidden', function saveCommand(){
    var cmd = jQuery.trim(U.__textBox.value);
    if(!cmd) return;
    var hst = prefs.getValue(PCache, '').split(Sep),
    idx = hst.indexOf(cmd), max = prefs.getValue(PCount, InitCount);
    if(~idx) hst.unshift(hst.splice(idx, 1));
    else if(hst.unshift(cmd) > max) hst.length = max;
    prefs.setValue(PCache, hst.join(Sep));
  }, false);
}
function wait4U(){
  var {gUbiquity} = Utils.currentChromeWindow;
  gUbiquity ? setup(gUbiquity) : Utils.setTimeout(wait4U, 42);
}
wait4U();
Cc["@mozilla.org/observer-service;1"].getService(Ci.nsIObserverService)
.addObserver({
  observe: function(subject, topic, data){
    subject.addEventListener('load', this, false);
  },
  handleEvent: function({originalTarget: doc}){
    doc.removeEventListener('load', this, false);
    doc.URL === 'chrome://browser/content/browser.xul' && wait4U();
  }}, 'toplevel-window-ready', false);
}