If you still think social networking sites are just for teens and college students who want to display their personal lives online, think again. Social networking sites also make great marketing tools. If you choose one that caters to your target demographic, you can set up a profile, attract prospective customers by offering interesting content and encourage people to go to your website or storefront. And in the spirit of guerrilla marketing, the cost is next to nothing.

One great way to start finding new prospects is by targeting your local area. MySpace, for instance, allows you to target zip codes. This powerful tool resembles what many businesses do in higher-cost direct marketing campaigns. You can go from having no contacts to a full list just by inserting a zip code or geographical radius specification.

Once you identify target contacts, invite them to enter your circle of networking friends. On MySpace, these contacts are known as MySpace friends and show up on your MySpace home page. Your new friends can be repeatedly contacted in a variety of ways, including bulleting posts, event invites and personal messages. Repetition is the key to any marketing. Doing it at no cost will impact your bottom line in a positive way.

But before you even start adding friends, work on your MySpace profile, which is very customizable. If you don't know how to spruce it up to your liking, you can hire a web designer who can help give your page its own look and add elements like music and video. You should also secure your own MySpace domain name (myspace.com/mycompany).

Your profile page gives you ample opportunity to feature products and services, awards you've won, specials you offer and general communication to prospects and customers. The same rules apply as for any other marketing: You still have to get attention, keep the interest of the visitor and motivate them to take some type of action, which includes contacting you or visiting your website.

You may also want to create multiple profiles for your business. You can create one for the whole company, feature key people or create a fictional character--think the Burger King--that can help market your business. You'll have the chance to reach more people and figure out what they best respond to. Just make sure you have the time to maintain your pages; you don't want to become a deadbeat business on these sites, and if your content isn't updated regularly, your network will lose interest.

Another benefit of social networks is that they encourage individuals to express their own viewpoints, opinions and ideas, making them a great place to do market research, including surveys. You can offer incentives to members for completing surveys, and you already have your members' basic demographic information to split them up into study groups.

Community involvement, if done right, is infectious. Better yet, it builds trust and confidence, which are the primary reasons people buy from you.