according to google's new algo... the directory submissions are not as effective as before.. but you should go for it... backlinks are never out of fashion..
Yes, Directory submission is useful to your website Google page rank. Directory submission is a technique to get the backlink. Google visit the site by using their specific function Crowder, and the backlinks are too important to increase the site ranking.
I've seen backlinks sold by the thousand for a couple of dollars - but have always shied away from them - just in case amongst those thousand are a few black listed sites - I worry that could be enough to bring down my whole network.