Say I have a site that I want to rank so I sign up at a bunch of Web 2.0s. I write an article (or rewrite an existing one) and put it on the money site. Can I use the exact same article and put it on all the Web 2.0s I create or does each money site and Web 2.0 need to have a unique article? Also, how much of the article do I have to change each time? Can it be a word or 10 words or more?