Idea's on keeping your dog cool during the summer

I used to have a little Pekinese that could not swim. When I put her in water (like a lake or swimming pool), she would turn almost vertical with just her little puggy nose sticking out and her short little legs paddling furiously. She actually enjoyd the water, but she could not swim. So I would put my hand under her tummy, like you do when teaching a small child to swim, and then she could happily paddle around in the water, and thought it was great fun. I guess she needed some "doggy swim wings" like they make for little kids.
I have seen the advertisements for the cool mats, and those do look like they would be a nice thing for a dog to lie on during the summer, but they would have to be somewhere that the water didn't heat up, or they would do the reverse, and heat the dog up.
My dog, Chipper, mostly stays inside, and I put a fan on the floor, and he will lie in front of that to keep cooled off on hot summer days.