Here is the walking quadruped robot that I created some time ago:
It uses simple self-balancing controller and keyframe based motions to walk. It turned out that 4 legged motion is pretty hard to get right. It took me quite some time to fix all the balancing and motion issues, so it can walk well. Turning left and right was especially challenging since it does not have enough levels of freedom in some directions. It uses 12 Robotis dynamixels (smart actuators). It seems like dynamixels and walking is quite energy efficient, since it can walk a very long time even on a small battery (2S lipo). It makes lots of noise when walking though. It can avoid obstacles with its ultrasound sensor and do cool flips 🙂 The Biolod coding language does not scale well when you try to implement complex logic. I guess the best approach is to control the robot from a PC (or netbook) and use on-board controller only for low level motion control due to its current limitations.