I just started a XMLDB users group within the Oracle Community started a few days ago by Eddie Awad.
My main idea for doing this, is to see who is wandering the XMLDB path as well plus, to see if this is an extra resource where people can help each other. This to ease the pain of the steep learning curve of Oracle XMLDB. Of course this is also a good resource where discussions are possible outside Oracle OTN XMLDB context.