After just having recovered from another power outage, I cannot recommend highly enough, the wonderful extension to firefox, known as SessionSaver. With that and CacheFixer (or by it's lonesome) it saves sessions between crashes. And the best part is that it's fire and forget. Install it, tweak a few options if you like, and then from then on if you have a crash, your pages will be back.
I've been using it on all my machines as of late, so that I can more easily pick up where I left off. Oh and I did mention that I had the ability to undo a close of a tab or even a window? How can you not love that?