Hey! I do this too. It's a not so great habit but the Treestyle tabs firefox extension does exactly what you need. You can select all tabs and click bookmark tabs. I actually recommend another similar extension called Sidebery*. It can even create occasional snapshots so in the case of a browser or system crash you have backups on disk or memory.

EDIT: Oops, meant to say Sidebery not Tabby. Sorry, wrote that just before bed. Tabby is a great terminal emulator though!