Tiddlywiki is perhaps the easiest to set up wiki available. You don't need a server. You don't need to setup a SQL database. You need to download 2 files, be able to run JavaScript and open the HTML file. It works on Linux, OS X and Windows as well as multiple browsers. I had mine set up and running in about 2 minutes flat and now I use it every day. What was the fix for that random problem? What's the login for that site? What's my long distance code? TiddlyWiki knows and it's even encrypted and stored on my a network drive that only I can access.
I would highly recommend everyone check this out.