If you've ever had the burning desire to torture yourself for all eternity by creating a necromancing, fiery eye from hell, then the Technology Studio in the U.K. has you covered. They did a 'Lord of the Rings'-style hack using XBox Kinect's motion-tracking capabilities coupled with a Pufferfish globe-projection system and made a creepy Eye of Sauron.
The infamous Tolkien evilmeister gives you the hairy eyeball and talks a bunch of doom and gloom while it tracks your every move. The Pufferfish technology has an internal projector and a Umami lens that displays on a 360-degree sphere. The Kinect takes the real-life coordinates of a person (Cartesian coordinates) and transforms them to polar coordinates, using the angle to move the eye. WPF and openni figure in there somewhere, too. The U.K. company outlines the whole process on their blog -- which they admit is not the most technically complex of all hacks -- but you get a freaky, all-seeing eye, so why complain?
Check out the below video of the spooky eye that you won't be able to kill with fire, because it eats fire for breakfast and stuff.