I had no idea.
Today, I came across http://en.wikipedia.org/wiki/List_of_Christmas_hit_singles . I only recognize around a quarter of these titles. There's a whole lot more out there than I had thought.
For those who may be wondering, "What Can You Get a Wookiee for Christmas (When He Already Owns a Comb?)" is available on the iTunes store in a cover version, but not in the original performance by The Star Wars Intergalactic Droid Choir & Chorale.