[coreyjon]

Correct me if I'm wrong, but "swerve" aka crab steering is very differant than skid steering.

Skid steering is when you have, for example a simple four wheel set up. The left side of your drive train is isolated from the right side, and both can be controlled independantly. The term "skid steer" derives from the fact that when you turn with this type of configurartion, your tires "skid" along the ground. Depending on ths surface, and wheels you choose, this type of drivetrain can put a lot of load on your motors, and stress on your overall drivetrain. A few years ago, we had a problem with too much traction using a simple skid steer setup, and had to put zip-ties on the tires to reduce the ammount of traction we had.