Web Directory is a collection of web sites presented in a categorized format....websites are categorized in such a way that internet users can easily navigate through them and find the website that they need
The more directories your site is listed in, the more inbound links your site will be seen as having, which in turn will improve your link popularity. Link popularity isn't the only thing to consider for SEO.
The more traffic you have, the more money you're going to make. Quite simply, I had websites but I didn't even have the CHANCE to sell anyone anything (and therefore make some cash) because no one was visiting my sites in the first place.