Normally when I brew I am using an aquarium heater to keep my ferment temperatures up, since my cellar is nice and cool year round. This Summer, however, has been brutal in Pennsylvania and my basement temps have actually risen to almost 80-degrees.
My most recent batch was the first in which I had to figure out a way to keep the temperatures down. I immediately went with the tub of water & T-Shirt trick to see its effectiveness.
Whoever invented this method is near God-like in my book. Fermometer reading has been in the 66-70 degree region since fermentation started. I have four 2-liter bottles of water that I freeze. Every 8-12 hours I put 2 of these in the water, and put the other 2 back in the freezer.
Again, if the inventor is out there somewhere, I'm definitely hoisting my next few pints to you dear sir (or ma'am).