While I've never had to resort to the trick (I make a point of removing and reinstalling my pedals ever couple months), I've heard that pouring hot water on the crank arm can help, since the aluminum will expand faster than the steel pedal shaft.
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This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.