A large unloaded stepper can put out 300 volts; smaller ones a lot less. However, this is the UNLOADED voltage. Load it down and it drops drastically.
Ever take two large stepper motors and wire them together? Works a lot like those old pre-1980 syncro systems, but without external power. You can't expect a step-in for a step-out, however.
I've used steppers as "digital" rotary encoders. Since the output of the two windings is in quadrature, they can be used to indicate rotation direction as well as "distance" from the number of pulses. Again, the idea isn't bad, but at low rotation speeds, you suffer in output and signal reliability.
Dean