Michael Manring. Ever heard of him? Check this video - he plays a Zon Hyperbass. This isn't your normal bass guitar. The hyperbass has a cam/lever system on the four tuning mechanisms in the headstock that allow the player to flip a lever mid-song and drop that string's tuning anywhere from a half step to a fifth. There's also a de-tuning mechanism in the bridge that allows the bassist to change the strings' tunings from that end of the guitar as well.

Enjoy.