I've quickly become a fan of Amy Winehouse. Check out her site at:
http://www.amywinehouse.co.uk/. (Advance warning: requires flash, and music begins playing right away, but not too loudly. You can sample 5 of her songs from the play menu at the top. My current fave is Rehab.)
Her music style is varied. Rehab has a 1950s/60s bluegrass/hills quality. Her other stuff reminds me of something you'd hear at a little cabaret, but with some guts to it.
She ain't Britney Aguilera or some other pop-flave shave of the minute. She's got a nice voice and some interesting vocal stylings.