I've recently moved my personal Wiki from UseMod Wiki to CGI::Kwiki. Both are easy to install, but CGI::Kwiki makes it easy to install multiple Wikis. For example I have a test Wiki where I can monkey around with things. It was as easy as,
The biggest selling point for me was extensibility of the software and that the data is just text files -- no database, no gdbm, no funky semi-text, no XML. Just fine for personal stuff, debatable if you're considering using it for the enterprise.
So now I run two copies -- one on my office Linux system, reachable over the internet, and a local copy on my Mac OS X laptop. I keep the two in sync by rsync-ing every 15 minutes between 9 AM - 6 PM via a cron job on the laptop. When I have net access, I'm hitting my Linux system, when I don't, I'm plugging away on my local apache on the laptop.