i must confess that i am not a big metal fan (not a fan at all, indeed) but to those who may be interested by metal female voices i will recommend
Le Tigrethe band is more electro than metal and the DJ there one of the very best female in hardcore electro... but...
BTW: I'm looking for the name of a finnish metal/hardcore band... unfortunately all what i remember about them was that they were in the tour for the 20 the anniversary of the british well known magazine The Wire (2-5 years ago)...
anyone has a tip about that?