Thanks to Last.FM, I stumbled upon a band called Angeldark, and they have a song called Libera Me that blew me away. I've enjoyed choir and orchestra pieces before, but this one is really up my alley. I was hoping someone might know of something similar musically and vocally. I don't know the right words to describe it, but I like heavier pieces. If you wanna skip to the vocals, it starts at 0:50.