Here's the robot I've been working on. All the aluminum is CNC cut and turned out pretty nice. The tracks and sprockets are from Lynxmotion and the drives are Sabertooth and Pololu. I've been driving it around with a RC setup but look forward to adding the EZ-robot controller I just ordered.
The center section powers up and the (face) is timed via a timing belt with the center rotation point so the smile always points forward no matter the position of the center section.
The sharpie drawn smile is just temporary and as soon as I can come up with a face that's got some character and can support a sensor or two I'll make it and install it.