I've been thinking of adding a radiant heater, like this:
http://www.amazon.com/Indus-Tool-CL-Flat-Panel-100-Watt-Radiant/dp/B0009HMFPM/ref=sr_1_16?ie=UTF8&s=hi&qid=1227215377&sr=8-16
The pluses are it's only 100 watts, and because it's a radiant heater it heats the chickens and objects, and...