Those chemical hand warmers that you boil to recharge are sure nice but they only last about 20 minutes, they do put out gobs of heat though. My wife buys the small hand warmers by the case for me at christmas, you can put them in a plastic bag and "shut them off" if you haven't used them up. I have electris socks but the battery pack is too bulky to get into my boot. I think they have improved over the years and I'd like to give them a good try.
We haven't talked much about fur:
The warmest mitts I have are native made out of coyote fur and lined with wool blanket material. I've sat at -30C (while rifle hunting) and my hands were fine. I might look at making some fur mucklucks, I think that might be the answer to my cold feet. Another Idea I've had is to go to the "goodwill" stores and fine a nice big fur coat, I'm pretty sure it would be as good as a lot of the modern miracle materials, and deadly silent too. Finally I have a muskrat hat that's dang ugly, but my head and ears never get cold with it, and my head doesn't get itchy after wearing it extensively like a wool toque would.