It's no longer enough to have an ad in the yellow pages. Direct mail advertising, leaflets, radio ads, billboards and television - who can afford all that? Cold calling and direct email campaigns can work, but they're time-consuming and difficult to target.
Every business and website needs to make sure that they are listed in search engines and directories. It doesn't matter how great a website design you have, if customers cannot find your site, you will not earn revenue.