I've been playing around with doing some quick UML diagramming to aid in communicating design and since I'm an IntelliJ IDEA user, I thought I'd give Beto Software's IntelliUML Teresa a try. Short story: works great for round-trip UML/code engineering. Very nice plugin and cheap for $149 for a personal license. This tool does a nice job of keeping UML and code in sync and offers some of the same IntelliJ IDEA refactorings in the UML view. Also generates class and sequence diagrams, in sync with the code. I highly recommend taking it for a 30-day trial spin. One note: Be sure to peruse the documentation on the site after installing the plugin. It does a lot of things by user context and its integration with IntelliJ is very subtle at times.