There is probably a huge amount of good stuff available from the people who are working actively with XML-RPC, Biztalk and other approaches to web services. More too from XML writers such as [http://uche.ogbuji.net/uche.ogbuji.net/ Uche Ogbuji], who has put much good stuff on IBM's developerworks site, among other things.
Sadly nobody has categorised or classified it in the Wiki, so at the moment we have to scratch around.