Continuously Rotating Servo
I just found this on HobbyEngineering.com and thought you might like it. I've read a few tutorials on how servo's can be made to rotate indefinately, and rather than doing that work, why not spend the extra $3 and get one already made that way?
So, here's a link and the description to one.
The Parallax Continuous Rotation Servo is now a Futaba S148 servo. It's recommended for robotics projects and includes an adjustable poteniometer to center the servo. Servos may be controlled directly from a BASIC Stamp I/O pin by using the PULSOUT command. The servo has been modified for continuous rotation at the Futaba factory. Its speed is 60 rpm at 5vdc (avg, unloaded) and delivers torque of 3.40 kg-cm/47oz-in.