Web 2.0 is a new generation of websites that allow the user to interact with them and essentially the users are what make the website grow. Big name examples of this are MySpace, YouTube and FaceBook. They allow the users to contribute their own content to the websites and also have a viral effect because the users tell their friends about the sites.
Hubpages is a small website at the moment and is relatively untapped, they allow you to contribute your own content to the site for others to read, also they encourage you to tell others about their site and give you a percentage of their revenue if they earn any money. Sounds like a good deal right? Go take a look at Hubpages to see how you can earn money.