Von Iva are probably my favorite all-girl band that're around today. For all-time, my favorite's Nico (Velvet Underground & Nico, solo stuff...).
I like girl rockers who don't have to be slutty to have an attitude: Siouxie & the Banshees Sophie B. Hawkins Blondie (ok, she's slutty, but she's Blondie for chrissake)
Not sure if anyone else likes these women, but I love em'... Patti Smith (duh) Kathleen Hannah (Bikini Kill, Le Tigre) Kim Gordon (Sonic Youth & various side bands) Lydia Lunch Exene Cervenka (X) Kim Deal (The Breeders, The Pixies) Tori Amos Bjork PJ Harvey Ani DiFranco Billie Holiday Patsy Cline Beth Gibbons (Portishead) Shit, I know I'm forgetting a ton...hope that helps.
Check out bands like.... L7 Butt Trumpet Bikini Kill The Distillers The Avengers Tilt The Donnas C.O.C.O. The Bangs Eyeliners
i've heard sleater kinny (spelling may not be right) is pretty good. Never listened to them, but just another band to check out.
Beth Hart Sara McLachlan Bonnie Raitt Rickie Lee Jones Melissa Etheridge Janis Joplin Marianne Faithfull Anouk Natalie Merchant Alison Moyet Eddie Brickell Suzanne Vega Indigo Girls Fiona Apple Michelle Shocked Tracy Chapman