I got really excited when I found out about peltier junctions, which are basically solid state heat pumps. Give them voltage and one side gets really hot, the other site really cold. They come in square plates that are about 1" wide. The idea was to make a refrigerator just big enough to chill one grape or a shot of vodka. I lost momentum when I figured out that they need a huge heat sink to be effective. I also realized I didn't know how to fabricate a 4 inch brushed aluminum insulated box that would look like a sub zero fridge. Also, I have a very functional full size fridge at the house.
I wouldn't put this idea up at all except that I was babbling about it in a bar to semi-famous poet Sam Witt and now whenever I see him he asks when his miniature fridge is going to be ready.
As a post script, while writing this I noticed that All Electronics has a peltier junction heating/cooling unit that's be salvaged off something else - All it needs is the fridge housing.