Researchers at the Delft University of Technology in the Netherlands have built Denise, a robot that walks with two legs. It has knees, an upper body, and two counterswinging arms. Its ankles help with stability.
Cornell University researchers claim their biped walking robot is "at least 10 times more efficient than anybody else's." They say it uses about the same amount of enery as a human--as opposed to Honda's Asimo, which uses 10 times more energy than a walking human.