The eccentric thinkers at asciimation have developed a phonograph using the Arduino. In the steampunk tradition, the turntable is steam powered and made from scrap parts. The speed is controlled by the Arduino using six magnets and a coil as a pickup. They use the PID controller library in controlling the servo based on the input speed. The Arduino drives a servo to move the throttle to maintain the speed at 33-1/3 RPM.
To add an equal measure of punk to the steam, the LP they tested it with is The Sex Pistols “God Save the Queen.”
For details on the project visit asciimation.
In aircraft they use tuned pendulums on the flywheel to absorb vibrations. an interesting property of such pendulums is that they give the flywheel an effectively infinite inertia (=> no variation in angular rate with varied torque) at certain frequencies of torque pulses. the REALLY intersting thing is that the frequencies of these pulse are per cycle, not per second. So it is possible to cancel out the cyclic torque variation due to having just one cyclinder. I think this would greatly improve the sound quality.
http://dspace.mit.edu/bitstream/handle/1721.1/11474/33363189.pdf?sequence=1
http://www.bhjdynamics.com/downloads/pdf/tech/BHJDynamics_Damper_Info.pdf