Hmmmm. I think for me, joining groups (and then participating) has generated the most for me. Participation is key. But it's something I'm always looking for so I'm curious as to the other answers you'll get.
yeah I definitely agree with Michele that groups like these help. I use these groups to discover other blogs that I like more than anything so reading other blogs that you enjoy and commenting does help too, advertising your blog on any groups (i.e. Facebook, Myspace) can be good
Writing interesting articles and submitting them to ezine or Digg would be other ways to generate traffic to your blog. Also, you can do some Search Engine Optimization in order to get your blog indexed in Google. For more info, you can check my blog @ www.feedbacksecrets.com
Leaving informative comments on other blogs really brings many users to my blog, but what makes users return? Information on the industry they are interested in, which happens to be the media on my blog, not for everyone but many are drawn to the events that are changing the way we all receive the news.