I think Diana K. is a great singer and pianist. I think she'll go down as one of the all time greats. To the list of other greats, add in Gillian Welch (w/David Rawlings - his guitar playing adds quite a bit to the music). She sings bluegrass / american folk music. Beautiful soft voice. I met her and david at a songwriter's workshop a few years ago. It was something to hear them in a small room with 10 other people. They had just released their first album, and were hoping it would succeed. I saw them on the cover of 'acoustic guitar' a few months later !