Oscar Perpiñán Lamigueiro is writing a book. Lots of people do that, of course, but Lamigueiro is doing it with Org Mode. Just the other day, I wrote that Emacs is multifaceted and Lamigueiro demonstrates another of those facets and a pretty high powered one at that.
If you've wondered how one might go about producing camera ready copy for a technical book, give Lamigueiro's post a read. You should also take a look at the Memoir Class documentation that he mentions in the post. I don't know about you but I love reading things like this. It's always great to see how people are using Emacs, especially if it's in ways I haven't thought of.