What is web2.0?

I know this is one example of web2.0 technology, however what is the business model for making money with web2.0 technologies? I really don't know the answer? If I did then I wouldn't be working for my company, and would instead have opened my own to make the money.

I have been working on some ideas, but they are really just ways to increase the user interaction on a web site. For the ideas I am working on, this is really what I want. It is based on all user interaction and user contributed content. I am also hoping to use a mashup with a couple of other sites, but don't know if there are API's for those sites.

I am also looking into the Rails framework. More on this later as I figure out what I need to get everything to work together. Since the application involves a database to track the user data, it is a natural language to use.