I second the recommendation for that book. But I may be a bit biased.
Seriously, if you want to see what types of things you can do with XDoclet, look at the table of contents. For example, going beyong
EJB, XDoclet can generate code for
servlets, tag libraries,
struts, JMX, web services, JDO, Hibernate, etc...
If you want to see HOW to use some of those non-EJB tasks then you can get started by looking at the XDoclet web site.
http://xdoclet.sourceforge.net But, you'll probably won't find too much documentation out there. That was one of the major motivations Craig and I had for writing the XDoclet book. Since nobody else was providing documentation, we did it ourselves.