The market-leading enterprise wiki,
Confluence, offers free licenses to non-profits!
A couple months ago I took upon the project of finding a wiki to use as an intranet for our non-profit (www.absoluteontheweb.com). I spent a great deal of time researching and then installing/testing a large number of different wikis (mediawiki, pbwiki, xwiki, pmwiki, wicca wiki, wikispaces, jotspot, wetpaint, etc, etc.).
I became very frustated at having so many choices for wiki software. I found that installed wiki engines (i.e. mediawiki or twiki) were far too tech-heavy to get functioning properely and not user friendly enough for non-tech users. Hosted wikis were much more user-friendly but either cost too much or lacked necessary features (google groups actually is looking really good now as a simple wiki). I had read about commercial enterprise wiki's (socialtext, confluence) that sounded wonderful, but were incredibly costly.
After pulling my hair out for far too long, I bumped across a website that mentioned free non-profit licences for Confluence (I wish that techsoup would have mentioned this!). I installed Confluence, and can safely say that is far superior in features and usability to other wikis. This recommendation is completely unsolicated, I just hope to save someone else the hassle in trying to find a great wiki engine. The only challenge with Confluence is that the install is a bit tech-heavy (setting up your own server). If you are a non-profit looking for an enterpise-level wiki/intranet though, Confluence is too good to miss out on.
Ryan W.
here are some wiki reviews, FYI:
networkcomputing.com wiki review
another review
confluence vs basecamp