Clare Seccombe's site has an amazing Christmas card idea in 3 languages.
Some resources from TES in French, Spanish and Italian.
Some culture from the BBC languages site in French, Spanish, and German.
Linguascope has some good Christmas resources (but you need to subscribe)
Lots of stuff on joyeux-noel.com
Stuff to do and print off at perenoel.com
Teteamodeler has some Christmas projects including recipes.
Primary.resources.co.uk has a page of resources which could be used for KS3, too.
mflresources has a page of Christmas activities.
Linternaute.com has a selection of Christmas e-cards you could send to your friends.
Hertfordshire Grid for Learning has lots of Christmas links here.