You'd think Thanksgiving would be harder since it revolves around turkey.
But no, I don't have any problems since I don't crave meat. But yeah, if I'm going over to someone's house for dinner I usually let them know in advance that I'll bring some "healthy" dishes--that way they don't have to worry about making something right for me, and I have something to eat.
And for Christmas it's really easy to make delicious vegetarian or vegan dishes. Just take your favorite recipe and alter it to fit your needs.
We should make an extension to this topic where people can post recipes and others can help to "tweak" them into good, vegan dishes. Mmmm!