Criteria: Haunting Music and Horror Sounds.

Creepy Dungeons Music by Allinardo

This music pack adds some slightly goose-bump inducing--perfect for dungeon crawling--tracks.
When paired with a mod that makes dungeons darker, it becomes very effective.

OMINOUS Dragon Soul Absorb Music by fadingsignal

Fadingsignal is a musician who has decided to share his talents with the modding community by altering the overly happy soul absorbing music that plays when you devour a dragon's soul. If you really think about it, it really is a really dark feat our dovahkiin is performing. This new foreboding piece accompanies the act of slaughtering a great beast and consuming its soul nicely.

Skeletons of Daggerfall by Bozzz123

The skeletons of Skyrim don't really sound scary. Ever heard the ones from Daggerfall (the second Elder Scrolls game)? When one of those skeletons jumped out behind you and let loose one their demonic sounding growls, you could feel the dread crushing in around you. This happy little mod brings all of that back.