Check out this cool find over at the nxtasy blog.
Ulli Kortenkamp has used bluetooth technology along with an Apple Macbook's internal gravity sensors to create a gravity controlled robot.
Ulli Writes on the You Tube page:
"In this video we show how to use the gravity sensor of a Apple MacBook Pro in order to remote control a LEGO MINDSTORMS NXT robot. They connect via bluetooth, and the Interactive Geometry Software Cinderella.2 is used as controlling software. It reads the data from the gravity sensor of the MacBook, processes it and then controls the motors of the NXT robot accordingly.
More info about Cinderella at http://cinderella.de, contact: email@example.com. Recorded at the University of Education Schwäbisch Gmünd, Germany."