I did some wiki research the past few weeks. I had some cri·te·ria to follow. It had to be open source. We wanted the wiki to work cross platform (Windows, Unix, Mac) and we had the freedom to mold it to our liking and build upon it. Another was that it worked right on the Apache server and used php. We didn’t want to fool around with MySQL. Another was it worked “right out of the box”. And finally, that it was easy for any person at any technology level to use. After the deploying test, the wiki we agreed upon was the QwikiWiki.
The install wizard was great and the freedom to change it was there. It used php and the config file was easy to edit. If you want to start a wiki, I recommend this one for all your basic wiki needs. It has great documentation on the qwikiwiki mark-up, a little confusing at first, but you get use to it fast. The runner up was the PmWiki. A little harder to change the CSS at first, but easy to install right out of the box and had all the basic wiki needs and good documentation. Check them out and enjoy!