I don't mean to butt in on the masturbation conversation , but I haven't seen anyone mention Ann Wilson (of Heart) yet. If you're looking for powerful female singers, you'd be hard pressed to find better.
Also check out some Joni Mitchell, especially her mid-70's jazzier albums (Court And Spark, Hissing Of Summer Lawns, Hejira, Don Juan's Reckless Daughter).
Those are two of my favorite female singers.

Also, check out k.d. lang, Bonnie Raitt, and Joyce Kennedy (of the funk-rock band Mother's Finest)

There's this band called Karmina, and it's a female duo. They both have really pretty voices.

I think the best female singers are Christina Aguilara, Madonna, Cranberries, Rose Rossi, Late Night Alumni, and Lauren Hill.

I really like Karmina too.
They have beautiful voices.
"The kiss" is always stuck in my head!

Karen Carpenter
Alison Krauss
Celine Dion
Annie Lennox
Whitney Houston
Dolly Parton
Reba McEntire
Juice Newton
Christina Aquilera
Cyndi Lauper
Mariah Carey
Blondie
Madonna
Belinda Carlisle
Sade
Toni Braxton
Loretta Lynn
LeAnn Rimes
Pam Tillis
Martina McBride
Sarah McLachlan
And about 100 others I probably left out.

I really like Anouk, Lisa Lavie and Joss Stone

Alice Smith is great.

Anyone heard of The Real Housewives of Orange County's Jo De La Rosa. She's so hilarious on that show. It's weird how she's going into music now. She pretty good for a start. Talk about great moving onto another career. I'm sorry Scarlett Johansson but Jo De La Rosa is doing it right. My favorite is "Letting Go." I'm a sucker for ballads. There are upbeat tracks too.

Translation:

Alica keys, Bjork, Sade,