Then try the band called Within Temptation.
Having just done 50 quid on iTunes today (it's too easy I tell ya) taking my iTunes buying total to 225 tracks since it opened the "just for you" recommendations are getting very accurate (especially if it recommends stuff you already have, you just tell it you already have it and it takes that into account with future recommendations). Apart from a load of olds tracks I liked and have added to my collection it also suggested an album called "The Heart of Everything" band called Within Temptation.
A very similar sound to Evanescence imho (Googling the band I think they've been going longer than Evanescence though).
(this is where I learn that everyone on the planet was already aware of them...)
