What does a blog DO for you?

If you only know a couple of people through a website (like goodreads) and you are an unknown author, then who would be interested in reading a blog? Do you write about yourself? Who would care? You would probably want to write about your book to generate interest as goodreads suggests. But if nobody knows you, then how would they find your page in the first place? If millions had already read Defender of the Realm then I wouldn't NEED to give it exposure, but by the time J.K. Rowling wrote book 7 I suppose she had no shortage of faithful fans who would be hanging in suspense for her next blog entry.
Until then, here is my first official blog entry. Maybe someone other than my wife will stumble across it.
If that someone is you and you are reading this now, go to http://www.coreyholst.com and check out my first novel: Defender of the Realm.