This is probably my second favorite Christmas album ever - The Bells of Dublin by the Chieftains.
"The Bells of Dublin/Christmas Eve"
"Once in Royal David's City"
"St. Stephen's Day Murders" with Elvis Costello
"Wexford Carol" with Nanci Griffith
And this song isn't from Bells of Dublin, but I ran across it while digging around on YouTube and had to include it. It's the Chieftains and the Decembrists doing a great Bob Dylan song, "When the Ship Comes In." Fantastic.