Here's an instructable showing how to Control a Hand Drill with an Arduino / roboduino to spool solder. This may not be on the top of everyone's project list, but a hand drill is strong enough to do a lot of tasks, so we hope this will be helpful to someone with another project idea,... maybe spooling guitar pickups.
Rather than use TRIACs to mess with the 120VAC, we found a servo was an easy and safe way to control the drill's trigger / throttle. The setup also uses a home made optical encoder that triggers an interrupt in the arduino code. The code is available here, and contains some useful bits like lookup-table speed control, state machine menu system, and interrupt based speed sensing.