I am not sure if most people subscribe to the blogs so this is a gentle push in that direction to take a look at the "unofficial competition" to get some cool PI developments using the Microsoft Kinetic sensor - a "Natural User Interface" to the PI system.
Check out my initial blog post about Skeletal PI. (There's a quick video of "Hello PI".)
Then check out Michael's blog post where he has a more comprehensive video of his awesome effort!
Disclaimer: Reading these blog posts will make you spend money on a Kinetc sensor.