A great source for winter camping info is www.wintertrekking.com
Unfortunately, someone hacked the site a while back for who knows what reason and wrecked the site. They hope to get it back up in a while. It is really a shame because that site was by far the best source for traditional cold weather camping tips, gear tests, you name it. Several members here besides me belong to it so if you guys are wondering what happened, that's the answer.

There is some info about the hack and the site owners' attempts to get it back online on www.bushcraftusa.com