Simple Tab Groups - Create, modify and quick change tab groups. Features:
Tab Stash - Tab Stash is a browser extension that helps you keep your tabs straight, saved, and restore them later.
Simplified Tab Groups - This Firefox addon provides tab grouping features similar to the removed TabView/TabGroups/Panorama...
SplitUp! - A fun and elegant tab manager
Panorama View - Tab Groups with Panorama View. Lets you easily Group and manage Tabs visually, with tab hiding.
Tab Session Manager - Save and restore the state of windows and tabs.