Appropedia is the main green wiki in terms of scope, activity and size, but there are many other sustainability wiki sites. Some cover green living, sustainable technology, construction, renewable energy etc, while a few attempt to cover all areas of sustainability.
Only a few are active and have substantial content. By far the majority have become inactive or abandoned without ever making much progress. (Making a successful new wiki is much, much harder than generally realized.)
 Active green wikis
The most active green wikis are, in approximate order from most active:
- Appropedia - broad focus on sustainable technology and practices, and appropriate technology for development and better living.
- Energypedia, focused on sustainable sources of energy, particularly renewable energy.
- Ekopedia - broad focus. (French version is most active; there is also an English version as well as other languages).
- Sustainable Community Action - activism & community
- Wikia Green, a commercially operated green wiki, focused on green living.
- Greenlivingpedia (site) - focused on green building, but also broader green topics.
- Tip the Planet - a wiki focused on green tips
- Critical Mass wiki - activism & community for cyclists.
- Hitchwiki, a wiki about hitchhiking (i.e. free transport)
- Trashwiki, a wiki about dumpster diving (i.e. waste reduction)
Another active wiki with a partial focus on green and development issues is the P2P Foundation wiki, more broadly focused on social and economic issues around peer-to-peer collaboration.
The above is based primarily on the data at Green wikis and development wikis - more wikis and a more detailed comparison can be found there, though some of the data dates as far back as 2008. (All green wikis can be added there - only the most active or somehow notable wikis should be added here - use the sortable table on that page to find the most active wikis.)
It is possible to search all these wikis and more at the Green Development Wikis Search.
 Past wikis
Many wikis have started and failed to grow; some wikis have merged into other projects.
Major merged wikis include WikiGreen, a substantial body of works on sustainable agriculture and more, merged into Appropedia in January 2007. More examples are at Appropedia: A history of collaboration.
 Why so many green wikis?
Why so many inactive and dormant wikis? Because it's easy to start a wiki, and easy to imagine something grand such as Wikipedia with a green angle, but in reality, making a successful wiki is hard. The daily commitment is a hard thing, the tech challenges are daunting (e.g. stopping spammers and vandals), and sharing the vision and building a community are huge tasks in themselves. So is it possible to build a wiki? Yes! But it takes radical collaboration.
 Broad or narrow focus?
The most successful wikis are often very broad in the focus topics - e.g. Wikipedia and to a lesser extent the other Wikimedia wikis, and Howtopedia. In these cases, all topics are covered, but the type of content is restricted.
The nature of a wiki lends itself to linking between related topics - thus a wide scope allows for a greater web of "wikilinked" articles. See Wiki synergy.
The approach of the Appropedia community has been to see articles on sustainability, green design, appropriate technology, renewable energy and international development, in their social, cultural and technological aspects, as part of a spectrum of related and overlapping topics, which are therefore best covered on a single wiki.
- ↑ Based on number of edits in 30 days (not counting spam/vandal edits and reversion of spam/vandal edits). The order may be out of date, and should be updated for 2012. The list ignores sites focused on pseudoscience, mainly zero-point energy, such as unproven, unsourced claims of running cars on only water - such ideas, when promoted uncritically, are a hindrance rather than a help to sustainability.
- ↑ Official site - formerly called "Wikia Green". This was set up by Jimmy Wales. It received significant media at the time of launch and at the time of a "call to action" by Mikhail Gorbachev, posted on the site, but has not yet gained major traffic or contributions, being less active than several of the other sustainability wikis. Even with Jimmy Wales' leading experience and expertise with wikis, his contacts with global sustainability leaders, and the support of Wikia, and even showing up consistently at the top of a Google search for green wiki, creating critical mass in attracting editors has not yet been attainable (still the case as of the end of 2011). This is an extremely clear example showing that making a successful new wiki is hard. Note: this is not to criticize, but to emphasize that even for the best people, this is a very, very challenging goal.)