Long time lurker to this area and I've learned more than a few things, so here's my contribution. Here's my ghetto(but free!) test rig for temperature control. Basicly it's the evaporator of a window AC unit imersed in a bath of water along with a heater core. Then water is pumped through the core and into a bucket surrounding the carboy. I had all the parts lying around, and my last batch hit 78 degrees even with the fan and tshirt method, so this is what I came up with just using parts I had lying around. I've been able to hit the mid 40's without really trying and can maintain 68-70 without any trouble on the stock thermostat. Next up is a real controller for it. Not sure yet if I'll use a comercial product or just arduino it. The plan is to put the AC unit in the garage but be able to pump the water into a seperate room/enclosure.