Santa Claus 1-3
How The Grinch Stole Christmas (animated)
Charlie Brown Chirstmas/It's Christmastime Again, Charlie Brown
Rudolph
Frosty
Miracle on 34th Street (original)
A Christmas Story
It's A Wonderful Life
Holiday Inn
White Christmas
Polar Express
Mickey's Once Upon A Christmas
Disney Classic Holiday Stories
I Want A Dog For Christmas, Charlie Brown
Muppet Christmas Carol
The Nightmare Before Christmas
Santa Claus Is Coming To Town
Star Wars Christmas Special
And, for some time now - my BIL and I have said that Die Hard and Lethal Weapon should be considered Christmas films, since they take place at that time of year. (Hey, if Sound Of Music can become a Christmas classic, why not Die Hard?)
eta - The above list is what we have, at least. We may have more, but I can't really go looking right now.