I saw this ad on craigslist... it's a 10 x 10 chainlink dog kennel with a peaked fabric roof. I'd imagine it would be pretty easy to put some netting in the eaves on the ends to keep preds out and chickens in, add a row of hardware cloth around the bottom, and you'd have a very nice run!!!
http://maine.craigslist.org/grd/607620005.html
http://maine.craigslist.org/grd/607620005.html