I live in Florida so I hadn't given much thought to the perch design of flat boards people have been recommending so that the birds can hunker down and keep their toes warm when temperatures plummet. Got me to wondering about the possibility of a heated perch and whether warm feet would warm the blood and the circulation would help keep combs warm enough to not freeze. If I were going to attempt one I'd probably use soil-heating cable used by folks to improve germination. You could rout a channel down the perch, drop the cable in and plug it in with a thermostat. The one I'm showing a link to can be set as low as 68 degrees. Since the cable is designed to be buried in moist soil, coop conditions shouldn't be an issue. The cable and thermostat seem like they would run about $60 -- rich for my blood, but its clear from some of the coop designs that $60 would be an incidental expense for some. Just a thought.