Rock in general is male dominated. But there is some ladies out there you should check out!

Nightwish: End of all hope

http://www.youtube.com/watch?v=p6xaIPszwpo

Angtoria: God has a plan for us all

http://www.youtube.com/watch?v=olFchpRcgao

Arch Enemy: Nemesis (one of the more agressive singers)

http://www.youtube.com/watch?v=wjBK0FYjmUY

Enjoy!