[Mike] dropped us a tip to show off a system he has built to control some power sockets based on his proximity. Initially the project started as a parallel port controlled box to switch the mains power. Then he got the idea of turning this into a little more interactive of an automation tool. He is utilizing the bluetooth from his cell phone as a locator. When the box senses that he’s in the room, the power is on. When he leaves the area, the power is off. You can see his ruby code on his web site if you wanted to give it a try or offer improvements.