Arch Enemy's addition of Angela Gossow on vocals for their 2000 album Wages of Sin was revolutionary at the time.  No other death metal band had a female singer, and Gossow certainly proved that she could scream and growl with the best.  Problem is, although she contributed, Arch Enemy is the baby of guitarist Michael Amott, and when he finds something that works he is more than happy to keep going back to the well.