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.

Session Buddy - Manage Your Browser Sessions

Tabs Outliner - Next Generation Session, Windows, Tabs Manager and a TooManyTabs Solution That Really Works.

Sessionic - A browser extension to save, manage and restore tabs and sessions.

SplitUp! - A fun and elegant tab manager

Workona - A better way to work in the browser.