I got a rusty rotor off by putting a bolt through the caliper bracket. You then thread a nut on, and tighten it, towards the head of the nut. This then acts as a jackscrew on the rotor, allowing a tremendous mechanical advantage.
When the rotor finally gave way, I saw sparks(!) come off of the hub. I had to cut the bolt in half to remove, as the force had significantly mushroomed the bolt end.