I have seen most of the ones listed and really think that most semi serious film fans would have seen or at least heard of them. There have been a ton of indie or older flicks listed.
But if you want something you may have missed thats older and screwed up, check out Phantasm. The acting ain't all that but its such a screwed up story you'll keep watching to try and make sense of it all. If you ever played Turok on N64, that game ripped the cerebral bore straight from this flick.
A movie I just saw recently in NYC at the Pioneer Theater that I thought was really good was Liberty Kid. Its the best 9/11 flick I have seen by a wide margin.