Well, I knew it was coming... and after 4 years I still can't stand the heat in Dallas. We have about 72+ days that will totally suck, but stay diligent about your chicken chores! Keeping chickens in the winter is MUCH easier than keeping them in the Summer. I let my chickens free range when its this hot, they know where they feel coolest (aka under the porch) So I place water close to where they will be. Just walking around will over heat a hen, so don't make them travel far for water. I also have a box fan to keep air moving under there.

Tips to keep your chickens cool

Water EVERYWHERE (but don't be stupid... a 5 gallon bucket of water is not the way to go. If its not good for a toddler its not good for a chicken. Keep the bowls/pan shallow.
Shaded areas. If you don't have shade, you better start making some. Here are some good options.
Water to stand in. I use shallow pans and keep them in shady spots. (Lola is a swimmer)
Electrolytes in their water (if they are panting / drinking a lot) will help replace the electrolytes they are losing. Get them here (give plain water & chicken-aid)
In moderate weather a hen may drink a pint of water a day. In hot weather, that amount nearly doubles. Two pints a day X 6 hens = 12 pints people!!
Fresh water throughout the day. (water left out in the sun will soon be warmed, so it is nice to replace it with new cool water every now and then if you can). A few ice cubes in the water can help keep it cooler for longer.

Cool fruits such as watermelon, can help cool and refresh your chickens on a hot summers day.

Ventilation in the coop.
Frozen ice packs - freeze 2 litre plastic bottles of water (or similar) as something cool that can be hung or laid on the floor of the coop or in a shaded area of the run for them to sit by or perch on if they want to. (if you can place the bottles in something like a zip-lock bag then they should be kept clean so that they can go back into the freezer ready for another hot day).
Cool fruits such as watermelon (straight from the fridge for extra coolness!) will help cool and hydrate your chickens.
A fan in the coop. A well ventilated coop may not need a fan, but in very hot weather if there is no air circulation the heat they expel from their own bodies can increase the temperature even further.