Bands that sound like Tristania??

nightwish, chalice (they won't like that...), there are tones of bands out there soing that kind of thing some better than others but give Chalice a listen they are a great Aussie band you could get their new album through Napalm records over in the states.
 
Amorphis - Black Winter Day (or night I'm not sure)This only one song and I've heard that they play very varied type of music.
 
Within Temptation- the album 'Enter'
Possibly also the first album by Green Carnation- "Journey to the end of the night". No death vox on it though (although Vibeke does put in an apperance), and it's mostly male vocals, and it's alot more doom than Tristania.
Not sure that Nightwish are that similar, they have a female vocalist, but the music is very different.