I *HEART* wiki’s.
I have created a couple of wiki’s for work and have really found them one of the “killer apps” of the Web 2.0 world. The ability to collaborate on a document is almost mind blowing. Also, I have participated in conference wiki’s, library best practices wiki’s, and blogging wiki’s. You can see some of my favorite wiki’s under my Wiki Wiki links on my blog’s sidebar.
Don’t know what a WIKI is? Just watch Common Craft’s Wiki’s in Plain English video and prepare to be amazed.