Creators, Synthesizers, and Consumers

http://www.elatable.com/blog/?p=5
Bradley Horowitz - Yahoo! VP of Product Strategy
"In Yahoo! Groups, 1% of the user population starts the group, 10% participate actively and may actually author content, 100% of the user population benefits from the activities of the above groups.

"Even in Wikipedia, half of all edits are made by just 2.5% of the logged in users... social software sites don't require 100% active participation to generate great value."