Otep is cool! I like In This Moment a lot too. In my heart, though, the queen of metal is still Doro Pesch, though her best work was the Warlock albums of the 80s.
A band that was really great in the power metal realm was Sinergy. Kimberly Goss had some serious pipes. But Alexi Laiho's other band Children of Bodom was the one that took off, leaving Sinergy to wither on the vine. That chick can sing though!
Then there was Phantom Blue, and Meldrum, featuring the late Michelle Meldrum on guitar. Damn, that girl could shred it up on guitar! R.I.P. Michelle, you kicked my ass!
The yearly "Women of Metal" issue of Revolver is my SI Swimsuit issue, but with talent I can relate to beyond looking good for the camera.