Best use of an existing song in a movie

Go Mama Said (Lenny Kravitz)
Pulp Fiction Jungle Boogie (Kool and the Gang)- in the opening credits
Serial Mom Daybreak (Barry Manilow)
The Social Network Ball and Biscuit (The White Stripes)
The Girl with the Dragon Tattoo(David Fincher) Sail Away (Enya)