#3 Tab Mix Plus What it is: Tab Mix Plus enhances Firefox's tab browsing capabilities. It includes such features as duplicating tabs, controlling tab focus, tab clicking options, undo closed tabs and windows, plus much more. It also includes a full-featured session manager with crash recovery that can save and restore combinations of opened tabs and windows. Why you should use it: Firefox alone does a decent job of restoring crashed session in a single window. This handles the restoration of more intricate window and tab layouts after a crash. Where to get it: Click here.