Didn't see this referenced on BF before, so here it is:
Behold, the ultimate winter cycling glove: the M1965 trigger finger mitt with wool inserts:
You can often find these for $15-20 for a pair of shells plus 2-3 inserts. Snoseal optional.
I have found that I physically can't wear these if it's above about 20F, as then my hands get too hot! (and this is coming from someone with a cold hands problem.)
They have enough dexterity to change a tube without taking them off.