I own both the gloves and mittens from Ice Armour and swear by them, although I agree with Stumper in that they don't breath well. I have never had cold hands when I remembered to bring them.
Another pair of gloves I use are called Chilly Grips (found them at a bait store near Bay De Noc, but now Gander Mtn. sells them). They have a rubber (quite flexable) palm and a synthetic top. They are great for handling fish and are nice on milder days. They work as a real nice bowhunting glove as well.