Meet BigDog, a mechanical mutt that does more than snare Frisbees and irrigate fire hydrants. It totes hundreds of pounds of gear so soldiers won't have to, and it will never spook under fire. Developed by Boston Dynamics with funding from the U.S. military, the BigDog prototype is arguably the world's most ambitious legged robot.

The squat, four-wheeled Robot driving itself through densely wooded terrain looks too macho to be cute, but it's too small to be threatening (picture a cross between R2-D2 and a Jeep). "You start to associate personalities with each of them," says Mark Del Giorno, of his 'bots. But still, Del Giorno, the vice president for engineering at General Dynamics Robotic Systems, which built this machine for the Army, insists that he doesn't anthropomorphize his robots: "You realize that the 'personality' comes from, say, the steering being a little loose.