The worm dance.
oh wait, we are talking tennis. I would probably have said volleys too (and i probably still will) but jeffrx has a good point. Especially with a one handed backhand, hitting a clean winner or even a passing shot when your opponent thinks he has you cornered is one of the best feelings in the world. Forehand winners too but they are a bit more frequent.
But yeah volleys are awesome. Especially after a decent point from the back and then you come in on a nice approach shot and hit a nice volley off your feet to win the point.