The Toshiba G55 Qosmio, great great grandson of those first Media Centre lappies that Toshiba put out, can use its webcam to process gestures and remote control your music, movies and powerpoint. One of the first. Laptop Mag says it works pretty well, if not overly sensitive at times.
They say it's thanks to a the Qosmio's powerful processor, but I'm not sure if I buy that. And anyhow, I don't like to waste spare cycles on something an infrared or bluetooth remote can do just the same. Plus, this sounds a bit too much like exercise. There's a video over at [Laptop Mag]