@Hobo-Ou:
If you dispise animal cruelty Aldrich, then might I recommend avoiding Lucio Fulci's Woman in a Lizard's Skin with it's grotesque dog disembowelment.
Yeah, I've heard about it. Never actually wanted to see it because of that. Same with Old Boy. I had my share of animal cruelty with Men Behind the Sun and Cannibal Holocaust.
Good choices, Eraserhead is great. Man Bites Dog is one of my favorites as well, mainly because of the main actor Benoit Poelvoorde, I consider this guy as a genius.
Another classic in the fucked up genre is Pier Paolo Pasolini's Salo or the 120 days of Sodom. Hard to stomach, to say the least.
edit I didn't see you mentioned it in your first post. My bad. There's also the new kind of horror movies like Murder Set Pieces who're to horror what gonzo is to porn, always more extreme, I'm not a fan of the stuff but that's still disturbing.
The Feebles, one of Peter Jackson's first movies, is also disturbing in that "have your childhood memories crushed by a shitstained boot" way.