Ross Mayfield pointed out a great new framework that Charlene Li at Forrester recently released called the Participation Ladder. It assigns quantitatively how many people in the US online population are mapped to various social engagement levels on websites.
I’m actually quite surprised at how active the online population (creators & critics) is portrayed in this study.
I would have expected the data to more closely resemble Bradley Horowitz’s Creators, Synthesizers, and Consumers model. In it he hypothesizes that 1% of people are Creators, 10% Synthesizers, and the remainder Consumers: 
It does make sense that online participation and creation is on the rise. Now, thanks to Charlene and Forrester we have the quantitative data to back it up. Finally, this ladder provides a roadmap for moving users up to more productive levels.