Tabs Outliner - Next Generation Session, Windows, Tabs Manager and a TooManyTabs Solution That Really Works.

Simple Tab Groups - Create, modify and quick change tab groups. Features:

Tree Style Tab - Tree Style Tab is an all-in-one Firefox extension that provides ability in order to operate tabs as a tree.

Panorama View - Tab Groups with Panorama View. Lets you easily Group and manage Tabs visually, with tab hiding.

OneTab - Whenever you find yourself with too many tabs, click the OneTab icon to convert all of your tabs into a list. When you need to access the tabs again, you can either restore them individually or all at once.

Session Buddy - Manage Your Browser Sessions