The DS Motion Card is a motion sensor addon for the Nintendo DS. It contains a 3-axis accelerometer, as well as a 1-axis gyro sensor. The creator was kind enough to send me one, so that I could play with it and make stuff for it to help him promote it.
Anyway, so far I have made a simple marble demo, tip your DS and marbles roll around. Currently it’s very simple, no collision detection or anything. I’m probably going to make a game out of it, simulating those little keychain toys where you have a few marbles, and you have to get them all into their respective holes.
NOTE: To build, it will require a CVS version of libnds, dated 2007-01-10 or later. Dovoto added ndsmotion code into libnds, as well as a nice simple example.