A couple years ago, we wrote about a robot called BALLU from Dennis Hong at UCLA--essentially a blimp with skinny little legs, BALLU made walking easier by taking gravity out of the equation. If your robot doesn't weigh anything, you don't have to worry about falling over, right? Inspired in part by BALLU, researchers from the University of Tokyo have developed a quadrotor with legs called Aerial-Biped. Designed primarily for entertainment, Aerial-Biped enables "a richer physical expression" by automatically generating walking gaits in sync with its quadrotor body. Until someone invents a robot that can moonwalk, you can model a gait that appears normal by simply making sure that the velocity of a foot is zero as long as it's in contact with the ground.