AiOS lets you open various windows as sidebar panels, and quickly switch between them. So it put an end to the window chaos! In addition to bookmarks and history it opens dialogues such as downloads, add-ons and more in the sidebar.
FEBE (Firefox Environment Backup Extension) allows you to quickly and easily backup your Firefox extensions. In fact, it goes beyond just backing up -- It will actually rebuild your extensions individually into installable .xpi files.
CLEO (Compact Library Extension Organizer) is a Firefox extension that works with FEBE* to package any number of extensions/themes into a single, installable .xpi file.
Note from Mozilla: This add-on has been discontinued. Try WebMail Notifier instead.
The original notifier for Gmail.
Add Unsorted Bookmarks Folder to Bookmarks Menu
moves the Bookmarks menu to the Bookmarks toolbar and makes it keyboard-accessible