The whole movie could apply to some, though most of it falls into Tear Jerker territory. The real NF here is Sara's descent into madness over the course of Fall and Winter. This sequence gives us such gems as Sara's POV of the world, which is menacing in every possible aspect, a refrigerator coming to life to eat her complete with loud, startling banging sounds, a TV personality emerging from the TV as a bizarre being made of static and mocking her, and the simple, horrific image of a completely fucked up Sara walking down a sidewalk in broad daylight. That last one also serves as the first image seen during the Winter segment, just to make sure you knew what the last third of the movie was about to be like.
Stripper: So what do you want us to do now?
Uncle Frank: Ass to ass. [Someone holds up a greased double dildo]ASS TO ASS!
The shock therapy, and the sounds accompanying the scene.
Appropriately enough, the corresponding track to this scene on the soundtrack is titled Meltdown. The music all by itself is NF. Kudos to Clint Mansell and the Kronos Quartet I suppose.
Harry's infected arm.
Anything in the "Winter" suite of the soundtrack, especially Meltdown.
"Lux Aeterna" is as creepy as it is awesome. More creepy, actually (except the orchestrated "Requiem for a Tower" version, which is just awesome.)