This thing is fascinating! I feel there is a a certain quality to Wiki, that it shares with things like TinyMUSH, that makes it feel a lot less "computery" and a lot more organic (it's not the WikiEssence, which seems to be to do with the ease of use, and transparency of the system - and MUSHes are not easy to use, certainly not if you are interested in building). You are definitely "in" it, rather than just looking or reading it.
The main topic of ExtremeProgramming is intriguing, but not something on which I have anything much to contribute. The structure and style of the system is very interesting though. So far, I've ended up ordering two books based upon discussions I've read in here (WabiSabi and ExtremeProgramming).
Oh - the bioey bit (I suppose the first bit ought to appear as a comment somewhere, but I didn't see an appropriate place for WikiAndXPNewcomerComments):
I'm a web developer for a Slough,UK-based ISP/ASP. Our main product is a turn-key e-commerce package, but my personal interests are more in the areas of online community and collaboration. Things like ZopeApplicationServer, Pyra and the way IMDb used to be.