I knew about the cone/pulley method, but the NuVinci one was new to me.
There's also a toroidal CVT (from howstuffworks.com):
Either way, a design for R/C would have to be a small/light package.
And as someone mentioned, the goal of this is not necessarily to use a smaller motor, but to provide a better spread of ratios, especially in the high-speed projects. Motors can only spin so fast, yet gear them up too high and you have cogging at slower speeds.
And linc, I'll just remove/disable any fan you put in there. Don't think a lack of warranty will scare me.
