Well I suffer from cold feet, but who doesn't.
I tried the Hotronic Heated Footbeds. The footbeds have a heating element under the balls of one's foot. A flat wire then runs out of your shoe to a lithium ion battery pack. The battery pack has 3 settings, which will heat the footbeds from 7 hours up 18 hours (depends upon the heat setting).
With temparatures in the low 20s, I tried the footbeds with a pearl izumi amfib booty and a thin pair of wool socks. With the controls set on medium, my feet lightly sweated and never got cold. Once more riding through frigid temperatures has become pleasurable.
I have the flat wire extension, so that it runs underneath my tights, up my leg and the battery pack clips onto my tights. This takes a little getting used to.
So far 3 rides and I am sold on this item. They are not cheap, as a full setup costs $165, but for me it is worth it, as I can now ride for several hours in comfort.