
Shade, shade, shade, shade.
I have an auto-waterer out to the coop, as well as several large troughs. During the summer, I put a solar-powered fountain in one trough to keep the water and surrounding area cool. For the other pens, I have multiple large water dishes that I change twice a day. The chickens like to stand in the water to cool off, which of course means they poop in it.
During the worst of the summer, I flood the runs, but what it comes down to is checking the water twice a day. Fill it once in the morning, and again as soon as I get home from work. I've done misters with limited success.
Also, the solar greenhouse fans, near a water trough, work really well. Swamp cooled chickens.
http://www.ebay.com/itm/Solar-Panel...ltDomain_0&hash=item2c636a3565#ht_1684wt_1396