In alphabetical order:

• A Christmas Story: I have this on DVD, but I always look forward to watching all Christmas Day on TBS! It's a classic!
• Christmas With the Kranks: Tim Allen & Jamie Lee Curtis are hilarious together in this movie!
• Christmas Vacation: This is my absolute favorite Christmas movie & it's also a tradition to watch every year.
• Elf
• The Grinch Who Stole Christmas: I hate the live-action version with Jim Carrey, but the cartoon is a classic.
• The Holiday: A romantic comedy centered around the Christmas holiday ... you gotta love the feeling it gives you.
• Home Alone / Home Alone 2
• I'll Be Home For Christmas:
• It's A Wonderful Life
• Just Friends: Not exactly a "Christmas" movie, but it takes place during the season so it counts in my book.
• Look Who's Talking Now!
• Love Actually
• Miracle on 34th Street (both)
• The Nightmare Before Christmas
• The Santa Clause / The Santa Clause 2 / The Santa Claus 3: The Escape Clause