Most unusual/mesmerizing female voice.

Antony, of Antony and the Johnsons. Though he's not female, his voice certainly qualifies. Many of my other favorites have already been named; Joanna Newsome, Margo Timmons, Nina Simone (sounds like Antony), Kate Bush, Tori Amos, Laurie Anderson, Carla Bruni, Diamanda Galas (personally a bit too much for me), Montserrat Figueras, Imogen Heap, Kate Rusby, Vienna Tang, Lhasa, Teresa Salgueiro (Madredeus), Karin Bergquist (Over the Rhine), Karen Peris (Innocence Mission), Frazey Ford (The Be Good Tanyas)....

I love female vocals...I could go on!

No one has mentioned Lisa Gerard (Dead Can Dance).

If you like Mazzy Star, check out Trespassers William (Anna-Lynne Williams/Lotte Kestner), and Lori Carson (Golden Palominos)

Levy03 - I share the same high opinion you have of her work with Mazzy Star. That music though requires, for me, that I be in a certain mood or it can be really depressing. In the right mood, I really love it. Absolutely it is mesmerizing and trance like. I also agree on her latest project with "the warm intentions" - I was disappointed by that effort. Agree on the heat level. Lori Carson is quite beautiful as well. I'd qualify the recommendations above: For Trespassers William, the out of print, "Anchor", which is an outstanding debut (hope they put it back in print so others can enjoy it without paying the $ it's now fetching), and "Different Stars" would be my strong preference over their recent effort. For Lori Carson, again, earlier work seems to connect with me more strongly; Golden Palominos "Pure" and "This is how it Feels", and Lori Carson's solo album, "Everything I Touch Runs Wild".

Jimmdavis - thanks for Lemonflower - I ordered her CD on CDBaby (backordered there) after listening to a few of her cuts on YouTube. Beautiful voice..just lovely. If you like her then definitely try Emily Barker - "Despite the Snow" is her CD ...just gorgeous! Here's a link for her song, "Nostalgia" (the video sucks ain't great, but it's the better of the versions for the audio that I could find). Oh, and Lhasa is a great recommendation too.