Most people should be working their way through New Vegas now or are already on their n-th playthrough. There would be folks like me still trying to finish Fallout 3. In case you’ve encountered one of Fallout 3’s nastiest bug, like I just did – crashing on save, this might fix it for you:
The cure: blow yourself up. I know, I know, sounds insane. But do it. Turn off all auto-saving if you need to, so you can reach your Fat-Man or whatever you want, but go blow yourself to pieces. Upon reloading your last file, it’ll undo whatever causes the save corruption
Some commentor on the second page said simply to load the same savefile twice. I did and it didn’t work. The problem was immediately cleared up when I went back to Megaton, got my fatman and blew myself up.