Commenting on sites with either related content or operated by people sympatico to my goals and beliefs.  It doesn’t scale super well, but it will get you started.

Your RSS reader is your friend here, helps track of where and when to comment.

Build my Twitter and LinkedIn network of likely readers and then push each new blog post out. (Of course, make sure you’re adding other valuable information and promoting THEIR stuff more, but make sure you get your stuff into the mix as well).

Write about long-tail keywords, to play off what @jeremyknight said. I win some pretty unusual searches, because no one else is writing about those topics or using those phrases.
Finally, I’ll ask a couple of very influential friends to RT my stuff as well. That’s helped out quite a bit because the traffic will take on a life of its own when a couple of superstar friends do that for me.

Social Media.

Twitter for exposure and traffic.  Typically links and hashtags for best results.  Tweet often.

LinkedIn for promotion (promoting self or business) and leads.  You can post in groups, answer questions you’ve made posts on and update to your LinkedIn feed.  This works more for b2b because of the platform but if you have a blog like SME where it’s more educational, that can work really well.

Facebook for engagement and leads.  Try asking a question about the post to help get your audience engaged on Facebook and possibly in the mood to leave a comment or share.

These are just a few social sites I’ve used that I know work and how I’ve found them to work most effectively.  There are other things like SEO which was sorta mentioned in previous posts (long-tail keywords) and what I think Glen was referring to… guest blogging.  

Guest blogging works if the blog you’re posting on is well established.