Looking for good recordings of female vocals I have not yet tried...

I assume Amy Winehouse has been mentioned…when she first hit it big, I had so much hope…truly knocked out…what a sad story she was…anywho…the music still lives…

+1 on Alison Krauss; in my opinion, the sweetest voice on Earth

While not solo, Voces8 have the best human voice performances and recordings I know of, and their soprano, Andrea Haines, must be heard to be believed.  

Enjoy.

Margie Day - worked a lot w/ Griffey Bros Orchestra. 
Ella Johnson - w/ Buddy Johnson

A few I enjoy but are definitely an acquired taste:

Circus 2000

Amon Duul 2 / Slapp Happy

Marina P

I don't think these were mentioned. e

Rhiannon Giddens

Petra Magoni

Bebel Gilberto

Brittany Howard 

Eva Cassidy, Songbird, Time after time.