Johnny Chung Lee is the PhD student from Carnegie Mellon University who has been rocking Nintendo fanboy hearts pretty hard by making the Wiimote do some spectacular feats. We first saw him track his fingertips on the screen for a "Minority Report" type of interface. Then he created an interactive whiteboard. Now, he's managed to create a headtracking simulation through the Wiimote, creating an amazing 3D window on the world.
The mod requires you to wear the sensor bar (or any IR-emitting headband, Lee makes some sweet goggles) and place the Wiimote by the screen (it's hooked up to a laptop with a TV-out for this demonstration). Essentially, your head becomes the mouse peeking through a 3D room, and the gameplay implications would be incredible.
Anyone else thinking that Nintendo should pay this guy whatever he wants to make some awesome games? Or, you know, Sony and Microsoft could always grab him up, too. These ideas just use the Wiimote's IR—technology that isn't exactly cutting edge stuff.