Jacob Christ, from PONTECH, put together a Ping-Pong levitation "trick" where ping-pong balls of various weights can be held up by a steady stream of air. Depending on the weight of the ball, the chipKIT-based Quick240 board controls the fan speed to keep the ball in the air.
Hackaday has featured a post about this very trick, if you'd like to read more about it. You can also click on the image above to view the post.