7. Alexa Vega & Tony Head - Seventeen
Second song from a musical in the top 20, and a bit of a cheat as this hasn't been released legally over here yet. But sod it. Yes, that is Giles from Buffy. Yes, that is the cute girl from Spy Kids. Yes, that is Joan Jett playing guitar in a cameo.
The musical is Repo: A Genetic Opera and it's like if Rocky Horror was directed by Tim Burton with music by Nine Inch Nails.