Hi!
I just ended a school project that resulted in AudioRacer, an FLOSS clone of AudioSurf, based on the game Racer.
You can see what it looks like here : http://projects.haxx.es/p/audioracer/
The game is not finished but I don't think we'll have time nor motivation to finish it.
So if someone feel likes working on Audio analyse and that kind of things, do not hesitate to take over this project!
Cheers