Ah, you should watch Adaptation. (Movie from 2002, directed by Spike Jonze.) Among other things, it's about adapting books to film scripts...
Fight Club is great both as a book and as a movie, for example. Of course it's impossible to maintain exactly how stylish the narration was, but the cinematography was cool and made up for it. Other than that, I can't recall many...
I'm reading Shutter Island now. I've read about half so far, but it seems the film is quite faithful to the original. The film has its faults, but I think it did justice to the book.