We've seen stepper motor control
tutorials before. However today's project write-up goes into much greater detail. It is an in-depth thesis on the topic of Steppers. There are also a plethora of links to different manufacturers and resources, all for stepper motors.
PyroFactor: 
May 17th, 2008 at 6:32 am
The longest journey begins with a single step.
The gives a very detailed description of stepper motors well done.