Peltier Junctions work by the Peltier effect (hence their name) which involves heating or cooling of the junction of two thermoelectric materials by passing a current through the junction. Semiconductor thermoelectric materials have greatly increased the effectiveness of thermo-junction for cooling. The Peltier effect is also the inverse of the Seebeck effect in which a current is produced in a closed circuit of two dissimilar metals if the junction is maintained at different temperatures, as in thermocouples for measuring temperature. The biggest problem is that they are very inefficient in energy conversion. There are a few other companies out there that also make coolers based on this principle, but the ones listed should give you a good starting point.
Offered by Steve.
There is a professor at Kansas State University that uses Peltier junctions to stabilize the temperatures of his laser electronics. He says that they are very efficient in small applications (low voltage requirements, reasonable current requirements) but wouldn't be practical in a large application such as for cooking or keeping a storage box cold (refrigerator) due to increased current and/or voltage requirements.
Offered by Roger.