[btilly]

Open source is an interesting example.

Normally there are transaction barriers that inhibit cooperation in providing public goods. However software has far fewer of those barriers. And so you get a situation where a network of loosely connected people each pursuing individual goals can collectively provision a public good.

I remember running across a footnote in The Logic of Collective Action saying that this was a theoretical possibility, but no example was known of it. (The book was written back in the 1960s.) In any case it is an extremely unusual example.