The best security you can get in a web browser!
Allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks.
Restyle the web with Stylish, a user styles manager. Stylish lets you easily install themes and skins for Google, Facebook, YouTube, Orkut, and many, many other sites. You can even customize Firefox and other programs themselves.
Customize application menus:
Rearrange or remove menuitems from the main context menu (right-click menu) and main menubar (File Edit View etc.)
DOM Inspector is a tool that can be used to inspect and edit the live DOM of any web document or XUL application. The DOM can be navigated using a two-paned window displaying a variety of different views on the document and all nodes within.
Helps you to save web pages and organize the collection. If you are using Firefox 18 or newer, use the beta, which is available on the development channel.
GMarks helps you sync & manage your bookmarks with Google Bookmarks...
Note from Mozilla: This add-on has been discontinued. Try Add-on Update Checker instead.
Notifies you when updates are available for your extensions and themes.