This is my third attempt at a wiki. The first two were slowly eroded by spambots, and that sucks. This time around, I'm using what appears to be the best wiki software (mediawiki), and I've decided on VERY conservative access controls.
Hosting is provided by dreamhost, to whom I am more than happy to throw money in exchange for their fine services. Seriously, I was way into running my own colo box for a while, but once I learned how to do it all, I eventually got tired of all the maintainence.