I’ve been doing some work with full-text searching in MySQL lately & came across a few solutions that could really use a wiki. So I wanted to recommend a free, hosted wiki solution, but the only one I’ve used is Wikispaces (which IME is slow & annoying). But I learned/read about a few others, so here’s a short list of free, hosted wikis, in case your community needs a wiki, but you don’t want to bother with installing/hosting one yourself:

• Wikispaces
• Wikia — built on MediaWiki (aka what Wikipedia uses)
• PBWiki
• Stikipad

There are many others, of course — wikipedia has a big list of wikifarms showing which ones are free. The biggest risk in using a third party wiki IMO is that they have your data, and if it’s a free plan and/or a small company, what guarantee do you have that your content won’t go “poof” one day & disappear? Oddwiki (one place you can get a free wiki) even tells you

“Nothing is permanent. Use at your own risk. We plan to delete all wikis that were not edited in 180 days”

Heh. So, that’s one reason I’d go with a bigger provider if you don’t feel like installing your own wiki (which is pretty easy to do if you have a server you can install one on).