Control Your Computer With Sonar

Now this was some very cool app, that i stumbled upon while surfing the net.. !
When installed and configured, it uses your laptop microphone and speakers to detect whether you are sitting near the laptop or away from it, and when you move farther, at a  particular distace from the lappy, it performs the action that has been written in its source code, for example, turning off the screen, opening your cd drive OR even opening a website, all depends on how you configure the source code !