To have you website be "visible" to the search engines, you need to get inbound links. By submitting your site to a number of quality web directories, you can have these links.
Inbound links help boost your ranking with Google, Yahoo, Msn and other major search engines. Besides that, the quality sites that link to you will also send you highly relevant traffic.
Increasing link popularity is important in search engine optimization (SEO) and effective linking can give a real boost to rankings.