There are many authors who have message boards where they can interact with their readers. Upfront this looks and sounds like a good idea. It has its pitfalls. Let me elaborate.
Cliques arise and new posters who disagree with the point of view of the ruling clique are ostracized. A case in point: I once posted an opinion on an author's board and it was not widely popular. The in crowd disagreed with me, but did they disagree with me up front? No, they started a new post, special for them, quoting and belittling my opinion and talking about how wrong I was. It was cowardly on their part and made me revise my opinion of the author as a person and her moderators (who of course were in the clique). I won't post there again. Will I buy her books? While she keeps on writing stories I want to read, and not stories the clique demand.
Which brings me to my second point, when an author changes the direction a book series is going in because the posters on her message board demand it. I've seen an author change rules of her world to accomodate what her posters want to see. It sucks, to be blunt. Most of the readers out there are off line - how are they going to keep up? Probably they won't and will stop buying the books, especially if the author makes the leap to hardcover.
My last point ties into the one above. Special stories that are only available on the website. Many times these stories contain content that's going to be germane in the next book and if you're not in the loop, you're really confused. And that's just bad business.