Johnny Chung Lee, a Graduate Student at the Human Computer Interaction Institute of Carnegie Mellon University demonstrates an awesome new use for the Wii Controller, Head Tracking.
Using the infrared camera in the Wii remote and a head mounted sensor bar (two IR LEDs), you can accurately track the location of your head and render view dependent images on the screen. This effectively transforms your display into a portal to a virtual environment. The display properly reacts to head and body movement as if it were a real window creating a realistic illusion of depth and space.
If all of this sounds a bit confusing, check out the video below. Hopefully more games will come out with this amazing innovation of existing gaming technology.