Heh, usually I just apply tons of force until something breaks (hopefully the bolt) and replace them with new bolts. On other things I have used a torch with great success. Usually heating something up until it glows a nice cherry color makes for ease of removal. I once removed a stubborn ball joint with this method, I tried everything else and since it was a tapered shaft cutting it off wasn't an option. After heating up the ball joint nice and red a few quick taps with the hammer was all it took.