Half an idea
A "Scramble" or "Moon Patrol" variant where the terrain is generated from a music CD supplied by the player. It wouldn't be the exact waveform as that'd be ridiculously wiggly (and therefore undriveable in "M/P"), but rather a function of it generated from the peaks and troughs. The same algorithm might populate the landscape with obstacles and resources based on the different sounds. And, if possible, any vocal with "Idol"-style oversinging – ie. holding too many notes for too long – would result in the loss of all jets or buggies, a hard-drive reformat and the electrocution of the user.