A lot of people don't know that award-winning film and stage actress Scarlett Johansson is also a vocalist, and while her voice isn't necessarily conventional or a powerhouse, I think she has a beautiful ass tone and great voice.
She has been doing music for a few years now, in between her acting. She did an album of Tom Waits covers ("Anywhere I Lay My Head"), a duet album with Pete Yorn, and a cover of "Last Goodbye" for the soundtrack of the movie He's Just Not That Into You, which she also starred in, among other songs.
This track, from a documentary called "Chasing Ice", was recently released.
EDIT: This song was one of the five nominated for Best Original Song at the Academy Awards this year. Hopefully that means she'll be performing it at the Oscars!