Viral marketing is also another way to get free traffic to your site. If a site is "viral" it will promote itself. For example, take a site I created when I was in college: Planet-Save.com.
Planet-Save.com is a web based e-mail system that allows members to save rainforest with each e-mail sent or received. When I launched the site (along with my business partner) I wanted to make the site as "viral" as possible, because I didn't have a lot of money to spend on marketing.
There were three viral components to planet-save.com:
1) Just the fact that it was an e-mail service. When people signed up their email address was UserName@Planet-Save.com. So whenever they sent an e-mail to someone, that person saw the Planet-Save.com URL. We know for a fact that many people saw the domain name and were curious about it and checked it out and then signed up.
2) At the bottom of every e-mail sent from the system we included the line:
Save rainforest for free just by using Planet-Save.com e-mail.
This was viral marketing at its best. It only took us a few days to get to over 100 users, and once we did they were e-mailing over 1,000 different people a day. Each of THOSE people received an e-mail that at the bottom said:
Save rainforest for free just by using Planet-Save.com e-mail
So in a very short period of time, we were reaching thousands of people with our message at no cost. Many of them signed up and then started e-mailing their friends, who then saw the message and signed up, and on and on. With viral marketing of this type it's easy to see why Planet-Save.com grew to over 10,000 members in just a few months, all without spending a lot of money on advertising.
3) The third viral marketing technique we used was the donations generated to save rainforest. It may seem like an odd business model to give away money to non-profit groups, but it actually works really well and it also feels good to be making a difference.
The fact that people could take something they were doing anyway, sending and receiving e-mails, and turn it into a way to make a difference was a huge factor in our growth.
But in addition to the viral marketing techniques used by Planet-Save.com there are many other viral marketing channels to use. Probably the best known and most utilized form of viral marketing is adding a "Tell a Friend" feature to your web site.
It's cheap and easy to do and allows your site to be spread all over for free.