Google Maps + Mandelbrot Set
You remember the Mandelbrot Set right? Mandelbrot was an IBM researcher working on visualizing iterative functions in the complex plane (I think) and he discovered this incredibly beautiful mathematical world which is now named after him.
Anyhow, it would be so cool (and useless) to see Google implement this. What better interface to roam around this infinitely-detailed bug-shaped world than the zoom and drag interface of Google Maps?