I'd like to read a good modern horror book, any recommendations?

I've read Swan Song by Robert McCammon and a few more by him and liked those. Also read The first Necroscope by Brian Lumley and liked that. Kinda like the Sandman Slim series by Richard Kadrey... :)

House of Leaves is a great one. I really lost myself in that universe.

I also enjoyed the novella Draculas. It was written by 4 horror authors.

If I had to suggest some author I'd definitively recommend Stephen King, although I didn't read his latest works yet. I consider Dean Koontz as another good horror writer too, although I don't know if all their work is good. I liked all what I read from them so far.

Edit: I've just remembered some time ago I read Richard Laymon's "The Woods are Dark" and it was nice, although looking for it (because of I didn't remember the title and I was wondering about this author) I found it was cut and there is an uncut version published by Cemetery Dance Publications in 2008 which contains some material which was deleted when it was first published by Warner Books back in the early 80's besides some extra modifications of the original work (Was it too much for the time?) I don't know, but I'd like to read that one though...

I started to read It, and it was SO god damn boring. I think he really doesn't hold up well.

Interesting you mentioned that book. I think one of my exes was reading that or read that when we were still dating. I'll give it a try.

Edit: regarding house of leaves.

Actually it's a little bit difficult to pick a single SK's book to recommend as a start for reading. I don't even remember which one was the first I read. I think it was The Shining because of the film, but it depends on what you're expecting for. The best suggestion is to read the synopsis on the back and go on if you get interested. One of the things that I like is sometimes he uses to cross characters from other books into the main story, that's funny when you know whom is he talking about. Not to mention his black humor that uses to be the cherry on the cake as I see it.

wonders of a godless world by Andrew McGahan

That's the one I'm currently reading in between breaks. Seems pretty Good so far.