SplitUp! - A fun and elegant tab manager
TooManyTabs - Ever tried having 20 tabs or more open in Chrome?
Tab Stash - Tab Stash is a browser extension that helps you keep your tabs straight, saved, and restore them later.
Firefox Sync - Bring your Firefox bookmarks, tabs, or passwords wherever you go with Firefox Sync. Share between computers and mobile devices. Get Firefox now!
Smart Tab Manager - Smart Tab Manager is a browser extension that allows you to save & restore your browser sessions.
Dustman - Firefox extension to close unused tabs.