Firefox also has the very useful "Restore Previous Session" option under the "History" menu - perfect for when you close your browser by accident (in case of a crash Firefox reopens last tabs by default anyway).
The tabs are also "soft-loaded" meaning that you have to click on them to load the content, so you can find the offending tab and kill it to prevent crash from happening again.
I use "restore previous session" pretty extensively, personally, especially if I have multiple windows open. That said, I've very rarely had bad luck with it in prior versions of Firefox, occasionally discovering that it's trashed my sessions. Thus, even today, I still keep Session Manager installed as an insurance policy. (Though, I still backup ~/.mozilla pretty regularly too...)
> The tabs are also "soft-loaded" meaning that you have to click on them to load the content
I couldn't be happier since Mozilla switched to this mechanism. It means reloading a massive browsing instance isn't quite as resource intensive. Last I checked Chrome/Chromium, it STILL doesn't do this, which is infuriating and part of the reason I dumped using Chromium as my primary general browser.
There's nothing worse than when as few as 100 tabs can eat up ~2-3GiB RAM right after you start the browser...
The tabs are also "soft-loaded" meaning that you have to click on them to load the content, so you can find the offending tab and kill it to prevent crash from happening again.