I created an intranet MediaWiki wiki for my company. As of 04-Feb-2008, this wiki has 2,924 pages that are probably legitimate content pages, 5,264 uploaded files, 341 registered users (account required to view_ and over 23 million page views.
I enjoyed it so much that I have created a couple public wikis. One of these wikis is dedicated to WiX. The other is for whatever I decide I need to write down for my own use. I've found MediaWiki a useful tool for my swiss-cheese memory.