Florin sent in this link to an interesting stepper motor controller. It uses a single ATmega8 to control all 3 of the motor controllers. Check out the web site for a video, schematics, and sources files for making your own. [Thanks Florin]
Although the motors are controlled by the same microcontroller each one can move independent. The board can receive commands to drive the motors trough serial interface from a computer. There is also a PC software that enables you to send commands from a nice graphical interface.
Read more about making a 3-in-1 Stepper Motor Controller