Going a bit old school here, but try Veruca Salt (2 lead female vocals) - a bit punkier on it, but fantastic stuff. The Donnas are a good middle ground - all girls, heavily KISS influenced, pretty kickass. Hole deserves an honorable mention for their earlier stuff (Celebrity Skin still is a brilliant album, despite how anyone might feel about Courtney Love), The Muffs for their slightly comic attitude to things. Anyone else? umm.. Die Mannequin, Furslide, Juliette and The Licks, Lacuna Coil, Letters to Cleo, PJ Harvey, Rasputina, Spinerette.. Think that'll do it.