Author Websites – What Are They For?

I have been considering setting up an author website (separate from this blog). I am, however not sure as to what such a site would achieve other than replicating material already available here.
One advantage to a website is that it displays static pages while a blog has content in more or less constant flux. A blog post which attracts many likes and/or comments today will, in a week or so be buried by more recent posts. However my blog already has several static pages which visitors see whe...