Finding a hosted, private, wysiwyg wiki
I've signed up for a couple dozen wikis in the last two weeks. In my spare time I've been trying to find a hosted wiki that meets our needs. We need a private wiki with WYSWYG editing, 40+ user count, reasonably fast edit transitions, hierarchical organization of pages, and ad-free versions.
So far the only two that really impressed me were wetpaint.com and wik.is.
Wetpaint.com has a $20/mo ad-free version for non-profits they are beta testing, but be warned that this only removes the Google ads on the side. The wetpaint-sponsored ads at the bottom can't be removed, although you can change their type by changing the 'category' of your wiki (try education for something safer).
Both can either be private or public, and allow template choices. wik.is allows you to create your own templates and edit the site CSS. Both allow custom domains and site logos.
Since wik.is is $99/year for no ads, and wetpaint.com is $240/year for less ads, I think we'll be going with wik.is.
Viawiki.com also hosts DekiWiki, and has a much faster editing version - give the demo a try. They license per user, though, so if you have a lot of people it can get a little pricey.