Sony's Eyetoy swordfighting game to battle Wii's MotionPlus to the death
Unfortunately, its motion is limited to the two-dimensional surface seen by the camera; any third axis motion would have to be interpreted from angle or what have you. However, it also allows for things like, say, putting your sword in your scabbard or holding it behind your back, things that would be difficult to describe in Wii gestures but could easily be done with the Eyetoy. Could be fun, could be weak — I look forward to finding out which.