Grab your Powerbook and head on out to a local amusement park. Thanks to the Apple Motion Sensor (AMS) built in to the 2005+ line of Powerbooks, there's all sorts of fun to be had with it in meatspace. A fabulous exploration of the AMS on kernelthread.com digs into the nitty gritty details of the underlying technology and provides some fascinating applications that play with the AMS. The Orientation Visualizer "displays a 3D image of a PowerBook 15 that appears to 'hang' in space. ... The orientation of the on-screen image is a real-time approximation of the computer's physical orientation."