I have been having alot of bicyclists ask me what gloves to buy so that their hands will stay warm in the winter.  My response is that there is no glove that will cut it.
 
I used to live and bicycle commute in upstate New York and I tried everything from lobster claws to neoprene without satisfaction.
 
The only thing that works came from my winter motorcycle riding experiences and they are called handlebar guantlets aka "hippo hands."  As compared to bulky gloves that prevent dexterity, hippo hands surround your handlebars and allow you to use a thin pair of summer gloves and not feel cold.  They keep the wind off you while your hands heat up the space inside.  Your hands may even sweat.
 
Yes, they may look funny, but if they can keep the hands of a motorcyclist (and snowmobilers) flying at 75 mph warm in the dead of winter -- the bicycle is a logical crossover.  Jill Homer, of Juneau, Alaska, rode her bicycle in the Iditarod Trail International 350 miles of wintry pedaling over tough terrain.  Note the hippo hands she is using in this NPR article:  http://www.npr.org/templates/story/story.php?storyId=16314506
 
This will only work on flat bars, not sure what to suggest about drop bars, except it was rumored someone was promoting a commerical version for drops this year at Interbike (www.interbike.com).
 
Here are some at overstock.com that might work:
http://www.overstock.com/Sports-Toys/Insulated-ATV-Handlebar-Gauntlet/3082719/product.html?cid=128296&fp=F&srccode=cii_13736960&cpncode=23-857477-2
 
Here is the company that bought the hippo hand name, the originals (which you can get on ebay) were made by craig vetter from 1971-1978:
http://www.hippohands.com/
--
Sincerely,

Jonathan Morrison
c: 801-688-0183