The American army has been fooling around with prototype Mecha since, like, the sixties, guys...
Hardiman suit;
http://files.gereports.com/wp-conten...e-hardiman.jpg
CAM (Cybernetic Anthropomorphous Machine);
http://dvice.com/assets_c/2011/05/ge...auto-63271.jpg
Unfortunately both were extremely expensive and tiring to control, never making it past the evaluation stage.
The good news is that the Bigdog is indeed pretty viable, through, and may well be used as a "pack mule" by the military in the near future. Which means that you'll probably be able to buy a civvy version eventually, just like the hummer. :3
This rather impressive walking crane thing has also been produced by timberjack;
https://www.youtube.com/watch?v=CD2V8GFqk_Y

