How about submitting articles to your own site? If you create your own original content, post your articles on your own site, and establish your site as an authority in its field. Some of my articles are 1,000+ words, I am not going to just give that time away to someone else. And that is what you are doing when you post articles on other peoples sites.
There are lots of sites with pr available for article submissions... try the google for the perfect list....or digg into dp forum