We've (me and a friend) been working on a publishing platform that revolves around keeping the connection between author and readers. Using my own book as test (about 2 months or so away from launch, first draft is in the editor's hand!): I write about learning the web and learning how to program, targeting people with no clue. So the idea of a "forum" was a given, I went a bit sideways from a forum, a searchable knowledge base, stuck on a chapter? Go on the website, check the knowledge base to see if other user asked similar questions, if not ask yourself and author will reply.

I think it's a win/win for both authors and reader, as an author this would enable me to update my book, clarify section that a lot of users are having trouble with, and for the readers it offers another dimension to a book, you can discuss it, talk to the author, other users.

I'll probably link it to HN when we are closer to launch.