So as of late I've been listening to a LOT of Atrium Carceri. This is because I spend the vast majority of my days reading and/or writing, and Atrium Carceri does really subtle, unimposing, creepy ambient shit that doesn't distract me.
However, I've also found that it's the perfect soundtrack for reading Lovecraft and Ligotti. Evenings when the wife's away, I turn the lights down, pour myself a whiskey, put on AC and crack open Songs of a Dead Dreamer or Grimscribe. Good shit.