In 2007, you're very short-sighted if you refuse to blog. Everybody and his grandmother is blogging. If you're a writer (or aspire to write) then blogging is a complete no-brainer.
A blog is especially valuable for a writer in terms of market research.
Let's see how this works.
You decide to write an historical novel. You blog about your characters, plot lines, and the time period you've chosen.
Unfortunately the response is - well, there's no response.
So you decide that maybe 2007 is not the time to pursue this project.
OTOH, if you're enveloped with enthusiasm from your blog's readers, or better yet, are contacted by an agent, then this is a flashing GO sign for the project.
In terms of market research, a few short blog entries have won you intelligence you could have gathered in no other way - or perhaps you could, if you were willing to spend thousands of dollars on it.
Discover blogging for writers, with my ebook Writing Success With Blogs.