Viral Marketing or Referral Marketing
Viral marketing is a marketing strategy that encourages and prompts people to convey and pass along a marketing message to others voluntarily. With viral marketing, your campaigns once started, would spread like a virus. Everyone wants to see it, and when they do, they all want to share it with their friends. This has many times the effect of regular advertising.
When starting Hotmail after having been left way behind by Yahoo! Mail, Bill Gates had resorted to viral marketing strategy to hit back at Yahoo! And he did it very successfully. All Hotmail messages that were sent out had a brief signature at the end of the mails requesting the recipients to sign up for their own free Hotmail account. In less than one year, Hotmail managed to capture millions of users!
You could sign up at one of the leading viral marketing sites at FreeViral.com. A viral site would be automatically given to you and you can register your Adsense site here and subsequently, anyone who is signing up at your site would be taken to your Adsense site. Of course you could also give some extra exposure of your viral site through article marketing discussed above.