Here's one useful and inexpensive method to let people know your web address. Design your site to be newsworthy, and then send press releases to publications who will mention you in their 'what's new' section. Make sure that you or your web developer has publicized the site in this way. Be sure to specify which categories and search terms to use when registering the site with search engines. Also ask about 'hidden search terms' and what extra services your designer offers to get your site listed near the top.
Many sites also practice offering 'reciprocal links'.
To do this, you find a site that complements yours, and offer to advertise it on your site, for a 'reciprocal link' on theirs. Usually no money changes hands in this kind of arrangement, depending on the relative popularity of both sites. It is possible to pay for ad placement that lures visitors to your web site. If your budget supports this method, it can bring thousands of surfers to a site overnight. Try and fond a small site that really focuses on your target market, to get the best bang for your buck.