But Elf. There's that scene where Zooey Deschanel is singing in the shower and Will Ferrell joins in on Baby, It's Cold Outside. It's delightful, and a little creepy, because Ferrell's elf is so socially awkward.
But elsewhere in the movie - or just on the soundtrack? - Deschanel sings it with the divinely anachronistic Leon Redbone. It's the best rendition.