Today's Mac download is A Very 3D Christmas Screensaver by Rob Bennet of Useless Creations. As 3D screensavers go, this one is pretty well done. You get to watch Santa fly through the sky and hop down chimneys from a number of different angles and the OpenGL rendering is fast and smooth. The saver will play your choice of Christmas carol (from a predefined list of 50+) and counts down the second to Christmas at you locale.

It is nagware (full version is $7.50), but it's not crippleware, and as an added bonus there's a Windows version, too, if you roll that way.

Previous 12 Days of holidays downloads for OS X:
Day 1, Day 2, Day 3, Day 4, Day 5, Day 6, Day 7, Day 8, Day 9, Day 10