I just heard The Secret Sisters (Laura and Lydia Rogers) on NPR's World Cafe yesterday and I am in love. When they sing their voices literally give me chills. Now I know how Ulysses felt.
Their debut album (produced by T. Bone Burnett) was just released and is available wherever you get music. In addition I HIGHLY recommend you pick up their single release 'Big River' produced by Jack White (of White Stripes fame.)
Their cover of Johnny Cash's Big River (with White on guitar) is a-freakin-mazing! I'm going to be playing it, like, all day today. You can hear it streaming online HERE.