I have also been active on the following Wikibooks:
XForms I have written 90% of these articles myself with a few other contributions.
XQuery I got a lot of help on these articles from Chris Wallace.
XRX -XForms, ReST, XQuery This is a wikibook that combines many of the XRX concepts into a single location to help understand the overall XRX architecture. I am the only author of articles so far but others are always welcome!
Ant This was one of the first Wikibooks that I wrote for Ant classes I was teaching.