I've been thinking about finding interesting use of content sharing "in the wild" and trying to codify and transplant them. For instance, the dojinshi comics in Japan are fan derivative works of commercial comics. They are tolerated and sometimes even looked upon favorably by publishers in Japan because they are part of a positive fan community and sort of promote the originals.
Many forms of Japanese poetry are based on derivative works and often allow people to republish them as a part of the norm. This provides a very vibrant community of sharing and "commons building".
Both have functioning business models that thrive from increasing "commons" and active creative participation by the "audience".
Do people know of other examples in other countries?