In this blog post, Fred Wilson says:
"Let's remember one of the cardinal rules of social media. Out of 100 people, 1% will create the content, 10% will curate the content, and the other 90% will simply consume it. That plays out on this blog, that plays out in Twitter, and that plays out in most of the services we are invested in."
The contrarian in me wants to dismiss this "rule." The right service just hasn't been built yet!
Is that naive? Will there ever be a platform that compels 25% of its users to actively creating content?