Time Projecting Red Laser Pointer
I think the ultimate geek toys are ones that use high technology to do things that are effectively useless or at least more inconvenient than conventional methods.
Case in point: the Time Projecting Red Laser Pointer which beams the current time to wherever you point it.
Completely useless, really. It's hard to improve on the concept of looking at your wrist to tell time, and yet...I really want one.