The sheer amount of XML configuration in Struts is overwhelming. I'm talking about thousands of lines. At some point, we were working with one single file, shared by a team of about 20 developers. You can imagine the chaos.
So, we started looking for a tool. I personally did a test drive on all the tools supporting Struts, including light alternatives like MyEclipse and behemoths like IBM RAD (used to be WSAD back then). There was only one tool which was acceptable in our case and it was called NitroX, developed by a small company called M7. Later on, it was acquired by BEA and renamed BEA Workshop, not to be confused with their incumbent BEA Workshop for WebLogic. The two tools were later merged and, eventually, found their way to the new owner, Oracle. It is now called Oracle Workshop for WebLogic. BTW, the only close alternative at the time was Exadel Studio, which was acquired by JBoss and became JBoss Developer Studio.
Last week, Oracle made an interesting move and decided to give it away for free (requires registration). The full workshop was an expensive piece of software, priced at up to $1000, if I recall correctly. What most people don't realize today is that this tool includes some Oracle/BEA specific parts, but also includes generic support for Struts 1.x, JSF and Hibernate and plugins for supporting Tomcat, JBoss, Resin, Jetty, and WebSphere. It is also a great tool for JSP editing. One of the few tools which came really close to near-WYSIWYG visual editing, with customizable design-time representation for JSP custom tags.
If you're using any of these technologies, I suggest you check it out. I haven't tried all the features, but I know that the Struts/JSF/JSP support is as good as it gets. It currently officially supports only Windows and Linux and can be downloaded here. It is a true hidden gem now, tucked away in the humongous Oracle web site.