Yep what Geoff said.....the peltier is a small flat surface that exchanges the heat from one side to the other...making one side very cold the other very hot...normaly this hot side has a fan to cool the heated side as much as possible...the cooler you can keep the hot side the colder the cold side will be.
Here is a picture of a Peltier....they normaly will run on 12 volt but come in various sizes.
http://www.oatleyelectronics.com/images/gp1.jpg