Camera-wiki.org is a successful, non-commercial fork of Camerapedia. It was built over the span of about a month, with a small team of volunteers reconstructing the wiki and its image database in response to a sale of Camerapedia to Wikia. Steevithiak tells the tale from the inside, of late-night perl scripts crawling through the databases reconstructing the site and of coordinated action to rebuild the photo pool.
The challenge of running a wiki is not only that you have to maintain a large collection of encyclopedic content, but also that you have to keep a pile of funky software running. The enticing trade is to accept advertising on your wiki pages in exchange for "free" hosting. The hosting company gets your community's sweat equity, unless they rebel en masse and go and build their own sandbox. More power to them.