I've been playing the free online sandbox physics game IncrediBots and I'm enjoying it. I'm tired right now but I wanted to post a simulation of a bot I created, which I'm calling "Multi-Extend Schrang." It has four pistons, with a motorized wheel on the end of each. It can handle a number of terrains. I'll be putting up a video soon of how it handles some of the obsticles I've tried to cross with it.
Controls: QWER to extend pistions (left to right respectively) and ASDF to withdraw pistons (left to right, again). Use the Left and Right arrows to spin the wheels (they all move at once). Notice that the bot can stand on only two or three pistons and still move.