It goes without saying that anyone who wants to promote a blog should submit his or her URL to blog directories. However, I suggest that it's also worth searching for SEO friendly free website directories as well. There are thousands and thousands of them out there. Most of the ones I've seen now have blog categories. They also seem to have three options: paid one way links, free reciprocal, and free one way.
If you're going for the free one way submissions it'll take a while, and you might get a few rejections. However, this is very straightforward to do. And you can be very specific about the sub-categories in which you post, which will of course help improve your search engine rankings.