While a wiki is fundamentally about collaboration, many of these small isolated wikis have found that setting up wiki software, engaging in preliminary PR and hoping a community will come is not enough. An extensive comparison of activity and resource size (number of pages) can be see at [Green wikis and development wikis], in a sortable table.
There are a few very active wikis, of which the most active by far is [Appropedia], which involves the broad community and particularly academics and their students (see the [Service Learning] page) in creating information resources intended to co-create a sustainable world.
CategoryWikis? CategorySustainability? CategoryGreen?