There are a ton of acceptable female fronted bands from back in the day and Dan's reference to the modern day and amazing Halestorm should be followed to the letter as they are truly phenom...
From days gone by: Lee Aaron, Warlock, Doro (after Warlock), Betsy and/or Bitch, plenty more I am blanking on I am certain.
Modern day bands that I have started threads on here: Kill For Eden is excellent and so are Ivory, there are some more odd ball ones I can not pull from the murcky depths of my wasted mind.