The Eye Of Sauron has been created using a Microsoft Kinect. A UK tech company called The Technology Studio have given life to The Lord of the Rings' main boss, Sauron. They used a Pufferfish sphere called a Puffersphere to project the eye and the Kinect's motion sensing camera to follow you. I'm a Kinect owner who rarely uses my Kinect but I always have it plugged in. As such I often feel like the Kinect is watching me as it moves when I walk by. With this hack, I will no longer think its watching me, instead I will know the vengeful Eye of Sauron is watching, waiting, plotting against me.
Source: The Technology Studio, they also posted a How-To.