StrutsCX looks like it could be interesting:

StrutsCX is Struts with XSLT - but without JSP. Therefore strict seperation of business logic from presentation brings development closer to the MVC pattern. In addition it always outputs well-formed XML (what JSP does not guaranty) and is much more flexible on the presentation layer.

This has some similarities to the XMLEngine code I wrote as part of Calaba's content delivery server (aside from the Perl/Java difference of course :) - this used a graph of multiple chained stylesheets to reduce the complexity and redundancy of any-to-any content transformations. [via whump]