I checked out the Omondo plugin for Eclipse. Later versions do a decent job at generating diagrams… but it doesn’t look like you can do much in the way of modifying code from the diagrams.
I’m hoping that some day a good tool for this will be made (IMHO there is no truly useful UML tool available yet) but I fear any tool that will please me will be way out of my price range
TogetherJ is already out of my price range and last time I checked it was next to useless. (The Omondo plugin is much more practical for real use.)
It seems that nobody actually “gets it” when it comes to these sorts of visual tools… the usability factor is astonishingly low.