@ sobre mi cadaver
Charles Bukowski and Irvine Welsh are somewhat similar in style and content. I haven't read the entirety of eithers works, but for Bukowski I'd recommend either
Pulp (short so serves as a good introduction) or
Ham on Rye (which seems to be everyone's favourite). Welsh might prove more difficult if you are planning on reading in English, because he writes in Scottish dialect which is hard to understand at first.
Trainspotting is a good book to start with, especially if you know the film.
And a couple by assorted authors:
The Cement Garden by Ian McEwan. It's a bit soft compared to Palahniuk, but still disturbing. It's about siblings who commit incest, I think saying any more would give too much away as it's very short.
Geek Love by Katharine Dunn. Again, not as blatant as Palahniuk but very original and strange. The novel concerns a couple who decide to produce children fit for a freak show, which is achieved through various interferences which hinder the development of the fetuses. It gets weirder and sicker as the children grown up, one starts a cult and convinces others to mutilate themselves, which causes a lot of conflict. Again, I won't give the whole plot away.
I haven't read much of Chuck Palahniuk and I've never read Danielewski, so these recommendations are just gritty and unsettling novels which I think are similar to the former's work. There's also a few YA novels I can think of, but I don't think you'd be interested. I feel like I've missed something huge out though