Ulver - Kveldssanger
Empyrium - Weiland
These are folkish acousting albums with a dark feeling.. try em out and see if they will suit the mood.
If you just want something slow and 100% unusual/creepy try these albums:
Ulver - lyckantropen themes
Ulver - a quick fix of melancholy
Ulver - svidd neger - this one has more modern feel to it