If you want to control your computer by just waving your hands in the air, you could do something challenging like hacking a Kinect system, or you could simply get this Tom Cruise in Minority Report style mousing glove.
I realize that the Minority Report comparisons are getting pretty stale these days, but this could practically have been a prop in the movie.
We saw a couple of brainy MIT students who managed to build something pretty similar a couple of years back, but the Ion Wireless Air Mouse is available to buy now for about $80.
This could be great for giving presentations, but I'm not sure I'd use it when simply working at my desk. Keeping your hand wrapped around a regular mouse all day can get pretty tiring, but I expect wearing a glove for hours at a stretch wouldn't be much fun either.