This novel application monitors the image seen by the built-in iSight camera and segments the image into little bubbles that make noise whenever there is movement behind them. The high quality sound effects are multi-layered and include:
Popping Plastic Wrap - the original concept
Gun Ambush - great for surprising flatmates and colleagues (especially if plugged into the stereo!)
Flies and Bugs - for Australians that miss home
Water Splashing - this is my personal favourite, the sound reacts really well to movement
Trumpets and Horns - like being jumped by a gang of clowns
Jungle Madness - don't move, there are lions (and parrots and monkeys) about
Baby Laughing - try this one out on the little ones
As well as being a thought-provoking digital experiment, Pop Motion is also great for playing pranks on colleagues and friends... see the home page for videos and tips!
You do, of course, need a standard built-in iSight camera for this to work e.g. MacBook Air, MacBook Pro etc...