Mindtouch Deki
I was looking around for an easy to use wiki and i evaluated a few, altassian wiki, flexwiki etc. Being a .Net developer, adherence to the .net framework was important for me, but this will be the first time i would be bending the rules. Mindtouch Deki is actually written in PHP, mysql. Well that wouldn't fit on the server would it? After doing a stint at MacBank working with MySQL and .NET guess things have mellowed for me somewhat.
I digress, back to the deki. The really interesting thing about Deki is that they bundle the app in what they term as a virtual machine, which is a vmware machine that you can use the vmplayer to run the app on the server. You can add srvany to make the vmware start up with windows. I think that is the coolest ideas I have seen for a while.