I've long had an interest in continuously variable transmissions (CVTs), going so far as to invent the Biaxial Idler for Continuously Variable Transmission, U.S. Utility Patent, No. 5,538,484 (July 23, 1996). I came up with that design while spending long hours bicycling, pondering the limitations of the customary derailleur. Typically for academic, though, I came up with something that works better in theory than in practice. Finally, though, some real engineers appear to have come up with a workable CVT for bicycles.
A fellow fan of human-powered technology recently tipped me off to Fallbrook Tech's NuVinci continuously variable planetary drive. As the first commercially-available application of their design, Fallbrook plans to market an in-hub bicycle transmission. You can see a very cool animation here. Tastes vary, I know, but I'd call the NuVinci design gorgeously elegant.
The NuVinci transmission holds the promise of improving not just bikes, but electric cars, windmills, and other useful things. I salute that sort of practical improvement, of course. Nonetheless, I also admit to having a soft spot for somewhat impractical tinkering. Hence my membership in the Human Powered Vehicle Assocation and my Semi-Prone Bicycle, U.S. Provisional Application for Utility Patent, No. 06/015856 (May 28, 1996). I doubt that, say, the pedal and propeller powered hydrofoil will save any lives. But it surely does no more harm than any other artistic work, and to some of us mechanical hackers it holds just as much beauty.