To start it off, I have two. The first was from Dante's Inferno. Right before the boss fight at the end of Greed, I fell through the floor and ran around a little under the map before I died, when it brought me back, it had completely skipped the boss battle and moved me to the next check point.
Another good one was Mass Effect, my character was knocked down by biotics at the same time as trying to use Unity, after falling he twitched on the ground and couldn't get back up, he then slowly began to stretch out until his neck covered 3/4 of the screen and the legs and arms were as thin as pencil lead.