I'll forget this if I don't save it

If you use a framework like Struts, you will find that your internal file paths don't match your external ones. So you may have /foo/bar/myThingy.action (externally) which is mapped to /WEB-INF/secure/jsps/myThingy.jsp internally.

If you use SiteMesh, the decorator patterns you put in decorators.xml should be mappings to your internal directory structure, not your external structure.