Session Manager can save, backup, restore, and manage multiple Firefox tab sessions. It comes with the option of loading the last saved session, not loading a previous session, loading a specific older session, or asking the user to choose. If it stopped there, it'd still be more powerful than the native Firefox session manager is but it has more to offer.
In addition, it can save more than 20 older sessions, and offers users several options for session management when closing Firefox. The plug-in automatically backs up sessions in the event of a crash. Users can also configure how the add-on displays the list of saved sessions, merge new and old sessions on recovery, and reload tabs on recovery.
Power users will love the plug-in, since they can configure how the sessions are named, change the saved session location, encrypt session data, and configure how postdata gets retained, even from encrypted Web sites. Since each session file created by Firefox includes text data, cookies, and history, as well as tabs, being able to recreate all that information effortlessly is a major headache remover that shouldn't be underestimated.