Peer Production Communities

Recently (June 2013), I've been having a lot of conversations around the question "where are the good examples of content (i.e., not software) PeerProduction communities?" I'd like to start this page as a place to build an annotated list of such communities. What communities have been effective, enjoyable, productive -- and what has led to that success? I'll start it off with a few.

• WikiPedia is perhaps the most obvious example. But is it truly "a community"? This term is used a great deal, but perhaps, with 100,000 regular contributors, it's better understood as a network of many overlapping communities.
• BallotPedia, JudgePedia etc. are wikis more focused on specific topic areas.
• The Wikia family has some very robust wikis: MuppetWiki, MemoryAlpha, etc.
• WikiEducator is a wiki without a lot of rules, with many people working on projects related to OpenEducation.
• OpenStaxCollege is a more focused OpenEducation project providing tools that permit collaboration on building TextBooks.
• OpenStreetMap is a great example of PeerProduction that doesn't exactly use a wiki.
• Many local wikis (many of which use the LocalWiki software) exist in many cities, for colleges and universities, etc.