Just this week I set up a wiki for the first time for actual use. If you’ve never used a wiki before then you can look here to get an idea of what they are and what they can be used for.
There are several Java wiki’s out there and after looking over VeryQuickWiki I settled on JSPWiki. That’s what I’ve set up at work for us to use to start organizing our project. Bobby Martin has suggested I take a look at TWiki because it has some additional features I want (like file upload).
I’m thinking of setting up another one here on underneath the UberCard project to support work on it and encourage others to contribute.