I had a chance to build the iitsii Robugtix hexapod and took some time to play with BigFoot Inverse Kinematics engine that comes with the platform. The engine really simplifies the gait management with the six legged platform. The build was easy, even though you have to manually position 18 servo motors by hand. The documentation is great and includes a serial command reference if you want to do some arduino interfacing work.
I have been working on a few different designs for a holonomic drive robot. A true platform like the other killough platforms made from Lego would probably contain wheels that rotate differently, but I wanted to publish this design because it is interesting.
I tried two different versions that you can see in the movie below. One version uses wheels but I also built this platform into a three legged walker.