That's kinda an 'open' question, but there's all kinds of Christmas things that go on during various times in the month of December... Mickey's Jingle Jungle Parade at Animal Kingdom, MGM Holly Day Parade, The Christmas parade will be running every day at the Magic Kingdom starting on December 21. There is holiday story telling at all the Epcot countries, Santa is at Downtown Disney (I think).
I'm not sure I've covered your question sufficiently, but hopefully this will give you some ideas!
Mav