I'm going to be running a Tabletop Roleplaying game in a few weeks, and the setting is an Ivy League College in the fall, and I want some dark indie music for ambiance. Like, black cloudy day in New England, leaves all off the trees, the first bitter slush of winter in the gutters, your tea just got too cold to be good, kind of music.
*Edit
All of these suggestions are awesome. My favorite I've found so far is
http://www.youtube.com/watch?v=77ZwHQI3J40
Thanks @nowaypablo @AshShields @Fuffle and @bfv
"Pride" by Phosphorescent is either really dark or tremendously uplifting, depending on the environment. New England in the winter, it'll be dark as shit. I know it's a little more than "indie," but Amnesiac by Radiohead is dark and claustrophobic. WIXIW by Liars is pretty dark. Anything by the Twilight Sad. Daughn Gibson is dark, but more in a "murder at the Mexicali border" way. Oh, also "Silent Shout" by The Knife, and "Unknown Pleasures" by Joy Division, although that one is kind of a sosumi for me.
For ambience, post-rock works really well. This might be pushing it, but for unsettling dark sort of tones I'd go for some John Murphy. He does a lot of soundtracks, but my favourite is easily the soundtracks for the 28 Franchise. Check this. Olafur Arnalds does some great stuff, too, though that track in particular might not fit entirely. Aidan Baker does some cool alt/experimental/indie stuff that gets pretty dark. I'd recommend browsing through his stuff to find something suitable.
Karl Culley. Let me know what you think :) Edit: Woops, I read your description afterwards and I realize this might not be the right "ambiance." Still, sounds like dark indie to me.