We've been working with a new client who wants to gain greater control over her book's online marketing potential (as in, life beyond Amazon). She had a web site, which was OK in look and content, but the site lacked the most critical component to selling your own book: an e-commerce portal. If a reader on the site wanted to buy the book, he was pointed to other online vendors, Amazon or Borders. While there's nothing wrong with those sales, why shouldn't authors instead capture their web site visitors and make them buyers exclusive to the author?
Adding a PayPal or other shopping cart button is easy to do. Even more effortless if an author uses a blog format for their web site. Most authors don't need to develop a web site from scratch. Instead, Obie Joe recommends using a template from blogspot, or WordPress and go. Many of these templates can be customized with the latest in e-commerce tools for just a few hundred dollars.
Even better is the ease in which authors can update and control the content of the site themselves. Having that ease makes the task of responding quickly to a marketing potential -- say, an article about the rise in YA vampire novels -- successful.