So why not use the Wiki Choice Wizard? It asks you some questions about what you are looking for in a wiki, and gives you a list of wikis that will fill that need. Seems to work rather nicely.
Of course, they don't include all wikis (could you ever include all of anything on the web?). I've used Schtuff to create a wiki, and I don't see that one on the list. Schtuff works alright but it does not do everything I would like it to. I wish I'd known about this site when I first created my wiki. Oh well, I can always migrate!
[Found on Download Squad]