Here is a overview of some commercial drivers, and if you do some searching on the internet you will find lots of circuits you can build. These motors are very popular (and rightly so) with hobbyists.
The motor in my Klinger stage has 4 windings and 6 wires. Each winding has 160 ohms of resistance. At first I thought it was a unipolar stepper, but it turns out it is a variable reluctance motor. I had hoped to use a bipolar driver for this motor (which is commonly done to run unipolar motors), but it turns out this will not work. But we are getting very much ahead of ourselves and ought to back up and explain some of these terms.
There are 3 kinds of stepper motors (actually there are more, but for purposes of controlling them, this 3 way breakdown does the job).
Bipolar motors are called bipolar because you send current first one way and then the other way through a winding. This makes the circuits to drive them more complex (you need to use an H-bridge).
Unipolar motors are called unipolar because current only flows one way through a winding or not at all. This makes the circuits to drive them quite simple (a transistor switch is all that is needed).
Variable reluctance motors can be driven much the same way as unipolar motors. Since the rotor is not polarized, it doesn't make any difference if current goes one way or the other.
It is fairly common to drive unipolar motors using bipolar controllers, and there are several ways to do it.
It is not possible to run the windings in a 6 wire unipolar motor in parallel, because the fields generated by the two windings would be opposite and cancel each other. An 8 wire bipolar motor can be wired up so that the windings are properly in parallel because you have access to both ends of all the windings. Doing this will give more torque, but less speed. Such 8 wire motors are often called bifilar motors.
Tom's Computer Info / tom@mmto.org