Tab Stash - Tab Stash is a browser extension that helps you keep your tabs straight, saved, and restore them later.
Toby - Better Than Bookmarks
Tabli - A simple, powerful tab manager
Session Buddy - Manage Your Browser Sessions
Workona - A better way to work in the browser.
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.