Toby - Better Than Bookmarks
SplitUp! - A fun and elegant tab manager
Session Buddy - Manage Your Browser Sessions
Tab Stash - Tab Stash is a browser extension that helps you keep your tabs straight, saved, and restore them later.
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.
Smart Tab Manager - Smart Tab Manager is a browser extension that allows you to save & restore your browser sessions.