Firefox includes an option for bookmarking all open tabs, but heavy users of tabs will find that this option is hardly enough. When you are researching a subject, the particular combination of tabs matters as much as the individual ones -- and, besides, selecting the tabs to open individually can be tedious if you are dealing with several dozen. And what happens if your session crashes before you have a chance to bookmark? You can address such concerns by installing Session Manager, a highly customizable add-on for preserving the state of the window after you close the browser.