That's the kind of dog i might want...

This dog is called a BigDog and is a robot. A quadruped robot that walks, runs, and climbs on rough terrain and carries heavy loads, and is powered by a gasoline engine that drives a hydraulic actuation system. BigDog's legs are articulated like an animal’s, and have compliant elements that absorb shock and recycle energy from one step to the next. Its a pretty cool way of carrying your shopping...