This was a really fun one, A four legged robot that took on many forms, including Batman's "Knightcrawler" from Justice League (below, left), eventually becoming a robot dog.
The robot used high-torque hobby servo motors and a 16-channel servo driver over I2c, controlled by the raspberry pi.
It could be controlled using a third-party ps3 controller, and included forward, backward, traverse left, traverse right, spin left, spin right, "lie down" and "sit" functions:
Featured here: https://www.youtube.com/watch?v=MelQNC1I7Ws
The final robot dog, assembled:
