If you're trying to do low cost marketing on the internet, one of the places people (or any variety of media sources) might recommend to you is Facebook, MySpace, and other social networking sites. While all of these can be great, you can be shocked or pleasantly surprised with what they are used for and how you can use them.
Facebook calls itself "a social utility that connects you with the people around you." It once was popular only among geeky college kids, but now is popular with people of all ages. It's still a great place for college kids to hook up -- most universities have a "community" and most of them are open to only members of that university. But it's also a good Web 2.0 application for online marketing. There are applications that allow you to add a business card, share links to your website, photos, books you're reading, music you listen to, and more. The clean layout is nice, too. This is an excellent place to start if you're comfortable with social networking and want to have some fun with your page and your identity.
MySpace is billed as "a place for friends," but I have found it much more relevant for people who have a band or are 12 years old. MySpace has the ability to easily load up songs for a startup garage band, and you can put your performance schedule on there as well. Beware though, the layouts are gaudy and the pictures and comments can be -- well, "titillating." It is a great way to get on the internet and spy on your 16 year old niece to make sure she's not pole dancing without your knowledge.
LinkedIn is the most serious and business-like network on the internet. If you're looking for clients, jobs, or to hire someone, this is your place. Hook up with former classmates, coworkers, friends in the neighborhood and post information about work experience, your company, or any other networking information. It's a lot less easy to personalize, but far more effective if you're networking.
Twitter is great for text-messaging addicts. I find it's a bit too tied up in the minutia of people's lives for my interest, but if your family and friends are nuts about texting, this may be for you. I have yet to really enjoy this medium, but perhaps it's because I'm not a texter, so I'm reserving judgment until I have a teenager.
All of these networking tools have ways to control who adds you as a contact or friend, and all of your information can be made private or public. They all also have ways of verifying your relationship with others, to make sure you are not sending (or receiving) spam. The downside is that there are people who set up profiles and never really check them again. Especially in more "mature" (ahem) age groups. But some embrace them and have a lot of fun with them - adding messages, etc.