In addition to my constant musical companions Ben Folds and Rufus Wainwright, another musical artist I love deeply is Nellie McKay. Her debut album, Get Away From Me, was incredibly inventive, with genre hopping songs (disco, torch song, rap, etc.) that were piano driven. I picked up her first CD after reading a review of a show, where mention was made of two things that piqued my interest: that she was very funny and politically progressive.
I was hooked after listening to the first three songs - I had the CD for about 2 months before I listened beyond that point. On the basis of the first three songs, I bought a copy of the CD for my older sister, who I knew would love it. She called me later that week and told me "I love her. She's a headcase, but I think that's why I love her."
Nellie's second CD is coming out in January, but you can preview one of her songs, The Big One, about a tenant's right activist, at Nellie's website. If you don't like it at first, give it a little time and listen again - it's unusual sounding, certainly, that Doris Day voice with a hip-hoppish accompaniment, but there's something good there.