So I'm rereading the Lord of the Rings
again, for the tenth time. As I read it I'm pleased to note that much of the dialogue in the movies came from the book. It may not be said by the person who said it in the book, but it's in there. For example, the song that Pippin sings for Denethor is a traveling song from the very beginning of The Fellowship of the Ring.
Thanks again, Peter Jackson.