Heh, this has to be one of the best discoveries out there. It turns out that if you have a Apple Mighty optical mouse, it can project a real mouse hologram on the desk. Try it. Update: We found it does the same on a Apple Wireless mouse as well, though this one looks like a "Mickey Mouse" from some angles.

PS: It seems the  Microsoft optical mouse projects a picture of a devil <just kidding> :)

Discovered by: Dan Bowles