well this post is going to be long but i like talking about music so if you won't mind.
you don't have to listen to all these but it would be great if you did.
here is Xandria alot of the music sounds like folklore music
Stream Of Passion they mix alot of electronic and violin with their music
For My Pain ... they combine male and female soprano voices
Epica is alot like Nightwish and WT
Leave's Eyes , she have a VERY mello voice, you might not like it but check it out anyways.
After Forever same as above.
Therion , This band started the whole "Symphonic Metal" thing and they are quite Kickass in it , witness the awesomeness of this song! 
Sirenia , you can notice her accent 
Theatre Of Tragedy , they combine very angelic female voices, and very "Growling" male voices, this type of music is called "Beauty and The Beast" Within Temptation was like this on their first two LPs, btw the female vocal is Liv (Leave's Eyes) before she got fired.
Rain Fell Within , they are quite on the "Progressive" type of Metal
and finally "Ayreon" and "Avantasia" imagine all the above being combined together with various other Metal types to form a band.
these two bands are actually not a "Band" its only various Musical icons hired by Arjen Lucassen (Ayreon , hes the guy with guitars on Stream Of Passion video) , or Tobias Sammet (Avantasia) which is called "Metal Opera" , as the albums tell a story and every singer is a character.
Note if you guess who is the female singer on this next two songs you get a cooooooooookkieeee
But like i said "Ayreon" and "Avantasia" are Opera Metal , so if you want the full experience and actually understand the storyline you should listen to the first song in the album and work your way to the last.
first suggestion is "The Human Equation" by Ayreon, its a very very atmospheric album and its a work of art that everyone should listen to from start to finish atleast once. you will be amazed
