Just a heads up, GOG.com have decided to change the name of their sale to something a little more grim in accordance with the "End of the World" stuff realted to the 21st. The sale has changed to the "End Of The World 2012 DRM-Free Sale" with over 21 hours remaining on their timer as of writing. They've listed a whole bunch of package deals, some of which that have been offered previously so if you missed out on those cheaper deals they are available for the next 21 hours. Additionally it hasn't been made clear whether the sale may actually end after the 21 hours rather then on the 3rd of January as previously advertised, so if you want to make use of those deals then now would might end up being the best time.
Source: http://www.gog.com/news/holiday_sale_end_of_the_world [http://www.gog.com/news/holiday_sale_end_of_the_world]
On a separate note, I find the reason for the name change of their sale really silly.
Edit: Well they went back to the way it was before.