Blogger Mike McCracken (who incidentally claims he is not a blogger)  recently put together a fun little project using an arduino, headphones and an accellerometer. It is an audio-only game of Ping Pong... with a difference. The accellerometer and arduino are mounted on the headphones, enabling the player to control the game with his or her head movements! When you put on the headphones, you hear a sound that is cycling through a sequence indicating its approach.

The sound is somewhere on the left-right axis in the headphones. If the sound is to your left, you have to tilt your head to the left until the sound is centered. If you tilt your head (the paddle) to the right position in time, you hit the ball an continue, the ball