From the pages of "Things That Will Freak You Out" comes:

BigDog

A quadraped robot or a "pack mule" as the group calls it. Saw this on TechTV last night (aka G4). Wow, everytime I watch this movie it just freaks me out. The thing moves so real and handles being kicked.

Here's the group's website: Boston Dynamics

I warn you, this is a bit freaky..especially w/o sound.