Tab Stash - Tab Stash is a browser extension that helps you keep your tabs straight, saved, and restore them later.
Symgi - Symgi - New minimal and pure bookmark site. Open multiple or singular links from bookmark groups.
SplitUp! - A fun and elegant tab manager
Dustman - Firefox extension to close unused tabs.
Tab Session Manager - Save and restore the state of windows and tabs.
Tab Wrangler - Automatically closes inactive browser tabs