Firefox 3.1 beta 2 (Mac) just crashed on me (well, it went unresponsive, and I Force Quit it), and I noticed when it came back that there’s a new “restore session” interface. Instead of just asking you “Start a New Session” or “Restore Previous Session”, you get to choose which tabs you want to restore.
This is super handy if you had a bunch of tabs open that you want to restore, but you suspect that one of them is what caused Firefox to crash in the first place. You can deselect the suspect tab, and still recover the rest of your open tabs. It’s no longer all or nothing.