Looking at the 12 V stepper motor at SparkFun, I came across a few other fun links. Including instructions for stepper motor wiring, a DIY surveillance camera, and an example project for the Arudino, using an EasyDriver Stepper Motor Driver. Also interesting, were the hardware suppliers: here's some clamping shaft couplers from ServoCity, and lots more from McMaster-Carr.
Finally, I was eyeing up on of the robotics kits at SparkFun: "The POP-BOT is an Arduino compatible, mobile robotic platform. It comes complete with wheels, motors, sensors, software, documentation, etc. The POP-168’s pin-out is similar to the Arduino Stamp".