A stepper motor to satisfy all your robotics needs! This 4-wire bipolar stepper has 1.8° per step for smooth motion and a nice holding torque. The motor was specified to have a max current of 350mA so that it could be driven easily with an Adafruit motor shield for Arduino (or other motor driver) and a wall adapter or lead-acid battery.
Some nice details include a ready-to-go cable and a machined drive shaft (so you can easily attach stuff). We drove it with an Adafruit motor shield for Arduino and it hummed along nicely at 50 RPM. To connect to our shield, put the wires in this order: Red, Yellow, skip ground, Green, Brown (or Gray)