The Ponginator is a three stories tall robot that can fire ping pong balls at up to 170 miles per hour. Its inventor, Vernon Graner of the Austin Robot Group explains:
Ponginator is a robot, and as far as robots go, this one is fairly simple. It plays music, says a few words cribbed from audio files, and shoots ping-pong balls from pressurized air guns.
A Parallax Basic stamp-based microcontroller in a computer behind the robot controls the robot’s ping-pong balls, which leave the barrel at 170 miles per hour.
Link (with video)