I came across this through Hackaday.com. This guy, Mike, built a temp controller to convert a chest freezer into a fridge. I thought this could prove to be useful for someone. He sells kits and completed models (which seem pretty pricey). If you scroll down the page he has everything needed to make your own (parts, diagrams, source code). All you need is some basic soldering skills and the know-how to program an Atmel microcontroller. I am not selling this, haven't bought it, and haven't built it. I thought I'd throw this one out there to see where it goes. Although, my instincts tell me not far.
http://screwdecaf.cx/yatc.html
http://screwdecaf.cx/yatc.html