I think you will get more replies if this was moved to the Parks and Strategies board. Only moderators can do that, so hopefully one of them sees this.
The Osbourne Family Spectacle of Lights at DHS - Usually come on at Dusk.
The Candelight Processional at Epcot - Get the dining package to ensure you get seating. They released those dates 08-26-10 last year, so check the Disney Blog and keep checking this site to stay on top of that.
Holidays around the World at Epcot- All of the countries in the World Showcase usually do something fun.
Mickey's Very Mery Christmas Party at MK- A hard ticketed event that starts at 7pm (can arrive as early as 4pm). It has special parades, fireworks and characters out. They serve free hot chocolate and cookies. A lot of rides are also open if you want to hit some with less crowds. They usually only sell about 20,000 tickets (max). These were released 05-21-10 last year. You do not need to buy them that early, but you can guarantee your date. I would buy them at least a few weeks in advance to ensure you get them on time.
The castle lit up in lights at MK- speaks for itself
All of the resorts have decorations and trees up too. A little resort hopping is fun to catch them. You can see the life size gingerbread house at the GF, the carousel at the BC and much more.
Downtown Disney has opportunities to meet Santa. You can see Santa Goofy there!
The Jingle Jungle Parade at AK- this is all I can think of at this park.
HAVE FUN!!!