I've been thinking -- always dangerous for me. :-)
I ran across this site a while back...
http://www.scrollerwheel.com
It describes a bearing/gearing system which utilizes ONLY rolling friction, so it's virtually friction free. A chuck mounted on a central output shaft could be fed from one of the planetary rollers, and ANY gearing ratio could be implemented. Just vary the size of the input/output rollers accordingly.
It looks quite simple to build. In fact, I just got back from Fry's. I've got some copper wire and some heat shrink tubing...guess what I'll be doing in my occasional free time? Making bearing assemblies to play with!
-- Chuck Knight