Florence Welch (Florence + The Machine)
Kate Miller Heidke
Nicole Kidman (Before she lost her facial expressions and tried her hand at singing properly, there was Practical Magic)
Josh Homme (Queens of the Stonage) - Lets not forget the men, shall we?
Other Notables: Julianne Moore, Shirley Manson, Alyson Hannigan, Gillian Anderson,Drew Barrymore
Those that should be stricken from the record: Lindsay Lohan, Reba MacIntire, Ginger Spice, Ron Howard (although he did make some pretty good movies)
I rest my case, your honour.