You Can Now Buy Spot the Robot Dog--If You've Got $74,500

Spot, Boston Dynamics' famous robot dog, dutifully follows my every command. The machine traipses forward, then automatically scrambles over a raised bed of rocks. I command it up a flight of stairs, which it tackles with ease. It meets its match when I steer it at a medicine ball, though; it takes a tumble, and for a moment lies paralyzed on its back. Such unfailing obedience, yet I'm nowhere near Spot, which is roaming about the company's testing grounds in Boston. With almost zero latency, I either use the robot's front camera feed to click on bits of terrain--think of it like scooting around in Google's Street View--or flicking my keyboard's WASD keys in the most expensive videogame imaginable.