Mouse2
Neat, here’s a 3D IR/Ulrasonic mouse project from students @ the University of California – “The goal of FRE3SPACE was to create a wireless mouse that could operate in three dimensions. In other words, while holding the mouse in the air you could move your arm left or right, up and down, towards and away, in relation to your computer. Our system would detect the 3D position of the mouse and give this information to the PC to be used by other applications.” [via] – Link.

Related:
DIY 3D Mouse – Link.