Die Hard, Lethal Weapon, and Batman Returns for the non-Christmas Christmas movies.
Straight Christmas films, pretty much the same as what everyone has already mentioned:
- Christmas Vacation
- White Christmas
- Home Alone 1 & 2
- Scrooged
- Elf
Honorable mention to The Star: my kids have been watching that like crazy for half a year now. Pretty solid and fun narrative surrounding Jesus' birth.