If you're looking for traffic, then a good search for high traffic forums and blogs would be a start. Next, you would want to put a forum signature on them and also do blog commenting. Finally, for even more exposure, guest posting would do the trick, but it might not be free.
Anyway, there are some other ways in addition to what has been mentioned. Nonetheless, I don't think you would get as much traffic - unless of course, you have something specific to offer. For instance, a typical forum promotion site would promote your blog, but unless your blog has to do with something other forum promoters want, like super deals on hosting, then I don't see how it would be effective.