The greatest user script engine on the Internet (a fork of Greasemonkey).
Status bar widgets and progress indicators for Firefox 4+
Add RSS icon back into location bar (URL) in Firefox 4.0. This icon was showed in Firefox 3.5/3.6 by default when page offered feeds.
Adds a small badge to your tabs to alert you to (for example) new messages on Facebook. The badge is also visible when the tabs are pinned so you can see when there's something new available.
Personalize your Firefox Title Bar! Anything placed on Menu Bar will be moved to Title Bar.
Don't like right-clicking? Use this restartless add-on to toggle your App Tabs with a double-click!
Central access point to Cookies, Content Preferences, Permissions, Form Data