Watched a great documentary on the Barkley awhile back. I've done a city full and a trail half marathon, but its mindblowing to comprehend just how rough this race is. For those not familiar with the handful of people who have finished, these guys are seriously tough. Brian Robinson has a wikipedia page (http://en.wikipedia.org/wiki/Brian_Robinson_%28hiker%29) that highlights his accomplishments, and the Barkley is one of them:

"Brian Robinson was the first person to hike the Pacific Crest Trail, the Appalachian Trail and the Continental Divide Trail (or the Hiker Triple Crown) in one year, a total distance of over 7,000 miles."

"In the years following the Calendar Triple Crown, Robinson became an active ultra-marathoner. He has completed several 100-mile races, including the Western States 100 and the Hardrock Hundred Mile Endurance Run. In 2008 he set the course record at the Barkley Marathons, a grueling 100 mile course in Frozen Head State Park, Tennessee."

Jared Campbell has also, I believe, won Hardrock previously.