We have a felt Christmas tree one with little ornaments, which DD6 will do each day. It used to be a tradition that the kids took turns putting up an ornament, and then we sang a song...but today DS14 left for school before DD6 was even awake, and she lost interest before we finished the song! I guess traditions have to change as the kids get older...
They each have their own chocolate calendars which I got on clearance for less than $3 apiece.