I'll post my answers first, and then read the thread to steal a few new ideas for DD this year!! 
I read a Christmas story at bedtime every night in December. I now have a stack of different Christmas books - mostly bought on sale after Christmas and stored away!! (Nowadays, as DD is 6 and wants long stories, we have a Christmas story and then a chapter or 2 of Famous 5 or whatever the current book is). I ALWAYS, since DD's 1st Christmas (born 26th Dec), have kept "Twas the night before Christmas" as the Christmas Eve book. It might get read again between Xmas and 6th Jan (it gets stored in the Christmas decorations box - the other books are stored seperately as they are needed earlier) - but never before 24th Dec.
Every year, DD makes paper chains. When she was younger, she helped hand me the tape and hold paper together. Now she goes off and makes them herself. I just give her a box of strips I have cut from coloured papers, and a roll of sellotape.
Potato stamping, for fun or for cards for relatives. Hand and foot prints for cards, t-shirts, pictures for walls or in frames - all for adoring relatives and an afternoon of fun messing!! Or do it onto large sheets of paper to use as totally original wrapping paper.
Baking things like cookies. DD loves baking - in her first Christmas, she just mixed the eggs (whisk with a fork before adding to the mix) and pelted flour with a wooden spoon. Oh, and rolled out a piece of (spare) cookie dough and cut out shapes herself (which were baked seperately and carefully not mixed in with the "real" cookies - but DH and I lovingly sampled them all with her!! :) ). In the past 2 months or so though, she has taken over entire batches where all I did was measure ingredients for her and she has made cookies and a couple of chocolate cakes all by herself.
Making things like Christmas trees, snowmen, snowflakes and angels by tearing folded up newpapers, to hang in a chain on the windows.
Lots of printable pictures from so many websites for colouring in. They go from very simple shapes and pictures, to very intricate. And there are some lovely ones that are not just pictures but add a touch of homeschooling or activity - like counting, letters, numbers, sounds, .....but all fun. Northpole.com was a great one (until it got blocked at work) - lovely activity sheets and colouring sheets, and even some great printable stories.
Making your own pictures. Cover a whole page in crayon - differnt colours at random. Paint over it all in black paint, and then scrape away an outline picture (Mammy part!!) with a knife/scissor edge - comes up in lovely mixed colours!
Gather pinecones on a walk and paint them as tree decorations. Cover in glitter for extra fun!!
Watching Christmas movies in front of a warm fire in the afternoons - could be a great saviour with a newborn. Maybe with some marshmallows and "reindeer poop" (chocolate covered raisins) to nibble on?
Writing a letter to Santa and posting it or sending it up the chimney. Did you know that Santa LOVES getting pictures too for his office from all the boys and girls??!!
Going to see Santa somewhere. We go on the "Santa Train" (an old steam train excursion) every 2nd year, and somewhere new on alternate years - I am thinking about a country house where they have a Narnia land set up in the grounds this year. I try to avoid shopping centre versions.
Going to buy the tree as a family - if you get a real one.
A shopping outing for the kids to get their presents. Could be a chance for DH to bond with newborn while you have even an hour with older ones.
Hot chocolate stops when shopping (with regulation marshmallows on top). Actually DD is not a hot choc fan, she just wants steamed milk always, even still - but always wants loads of marshmallows.
A charity day - going through old toys to give to a charity shop or somewhere suitable for kids who don't have as much as you. Can be a chance to get rid of too small clothes too. Or, if that isn't feasible in your house, just thinking about other kids who don't have a lot and doing a shoebox for one of those appeals, or taking a tag from a "giving tree" and getting a present for that person.
Put on some Christmas music and dance around the kitchen/living room!!
If dry weather, go out and blow bubbles. If damp weather, go out in wellies and jump in puddles, and feed the ducks. If wet weather, have a carpet picnic indoors.
One evening, go out to look at any lights after dark - either a walk or in the car all snuggled up.
Track Santa on Norad website on Christmas Eve (great way to get kisd moving towards bedtime!!). There's also an app on ipod for how many days til Christmas - DH has that and brings it out occasionally during the year, but then most days in late Nov/Dec!! (And then tries to tell me he doesn't love Christmas!!)
My brain is now a bit mush and I can't find my list that I have safely stored in my pc, sorry. Hope they're some help!!