Here's a nice little example of what you can do with XUL. It's useful to note that the Mozilla browser interface is itself written in XUL and Mozilla Themes are commonly written by copying the main Theme, modifying that template's XUL, CSS, JavaScript, and images then repackaging it into a new jar file.
Also, I read the beta chapter on Servlets from O'reilly's upcoming Java Enterprise Best Practices. Not too bad, even for an Enterprise book.
# — 09 December, 2002