the lady from Everything but the Girl Bjork (especially when she was with the Sugarcubes) Pat Benatar (although "Hell is for Children" has to be the most bluntly stupid song title ever) Chrissie Hynde And I have to give props to B.L. who sang in my band from 96-98. Although her voice was a little ragged at times, she came up with some of the most beautiful melodies and lyrics I've ever heard.
Tracy Thorn is a good one and another that I forgot to put in my honorable mention list. Walking Wounded is a great CD to get of theirs if you like down-tempo stuff with a little techno thrown in.