Chris Pirillo pointed out some software from BananaSecurity which uses a webcam to recognize your face, lock your computer when you're not there, and unlock it only when it recognizes your face again. Obviously there are some questions about this, like what if I'm wearing a hat, what if it's darker/lighter, how secure is the lock it puts on your computer, and what if I want to use the webcam? Course, it still interest me greatly as the laptop that work got for me has a built in webcam on it...