Ok so those not familiar, a Peltier cooler is a type of thermoelectric cooler:
Series wired PN junctions are placed thermally in parallel to each other, as current passes through the junctions, the temperature on one side of the device heats, this heating effects causes an opposite cooling effect on the other side, efficiencies are very poor at around 5%, compared with a domestic fridge at around 40%, so not very efficient, and therefore has very niche applications mainly in the areas of active cooling. Interestly; these devices can be used to generate electric by heating one of the plates, imagine if we could reuse the heat from our car engines to conserve power (Problem with this is that the max temp of most of these devices is around 150 degC....unless they were stacked?).
Anyway here is a pic (thanks Carl!), of a destroyed Peltier, which luckly split in half so we can see those PN junctions:
I would be interested to know of any weird and wonderful applications for these devices!.