Thought this might interest some people. It's a video clip of an advanced quadruped robot called BigDog that's incredibly adept at keeping balance and traversing slopes and bumpy surfaces. There's one part where a guy comes up to it and kicks its side, and it staggers to the side and regains its balance, looking very natural in the manner it does so. Another really cool part is when they get it to walk on ice, and it slips a fair bit but still stays balanced.
[youtube]http://www.youtube.com/watch?v=W1czBcnX1Ww[/youtube]
When you've watched that one, watch the next video which shows the next model in action.
[youtube]http://www.youtube.com/watch?v=TKKzUfe46sU[/youtube]