Nice informative link. I think its also important to see if the links within the directories themselves are being indexed and show up as backlinks in googles search.
uyur;189759 wrote:
Most directories will only help you increase PR and SERPs. However, there are some niche directories that get search engine traffic and some of those clicks make it back to you. Take a look at the directories in your niche then try a google search for some of the long tail terms on their page and see if they come up.
http://www.allydirectory.com/blog/2008/04/06/how-to-choose-a-quality-web-directory/