Partial List (more people will be along)! I have no idea what's traditional where where you are, so I'll list everything I can think of!

Consider buying Delia Smith's Christmas Cookbook (on UK Amazon
here which has lots of traditional British recipes. If you prefer you could subscribe to her website
here, which gives you lots of the same recipes.
As general food, a good large fruitcake and a chocolate yule log are always baked in our house (
clicky for history of a yule log, and
here for a photo). Mince pies are also very popular - see
here for a good recipe).
Turkey, roast potatoes, sausages (possibly cooked wrapped in bacon with a cocktail stick stuck through to hold it in place). Yorkshire puddings, sprouts (which should be prepared carefully -
clicky. Of course there should be other vegetables - we have carrots, cabbage, etc, wholegrain mustard, gravy, etc.
Crackers on the table to pull after the starters are also popular -
http://www.oldenglishcrackers.com/make-your-own-crackers.htm . You can buy cracker kits if it's hard to get 'cracker bangs' where you are!
The best bit is dessert which is usually Christmas Pudding with Brandy Butter. It's traditional to douse it in flammable alcohol (cooking brandy) and then touch a match to it so it's surrounded by light flames when brought in. It doesn't burn the pudding but be careful.
That's all I can think of right now, I'm off to finish my sewing. Have fun!