Like last year, SE is doing their Winter Hat promotion again. There is an opt out for anyone that individually doesn't want to participate, but my plan is to opt in our community unless there are significant objections.
The hats come out from December 16th until January 3rd. You'll be able to see all of the hats at http://winterbash2013.stackexchange.com once the event starts. If you have a deep hatred of hats, there will be a "I hate hats" link in the footer that will allow you to individually opt out.