I have a complex application with lots of class files. I'm using Doxygen to generate some documentation, but would love a tool that can statically analyze my code and generate some UML diagrams. Not sure if a product like this exists, but would love to hear the community input.
There are many tools doing exactly this on various levels of quality. I would like to mention that generating UML diagrams for documentation purposes might not be a great idea, especially in large projects. The problem is that in complex code bases, there are many relationships between classes, a lot of code is called, etc., basically, any diagram type you choose might, in a particular project, look bloated. A confusing diagram might be worse than well-structured textual documentation. The main idea of modeling is to abstract from unimportant details, and deciding automatically what is unimportant is not easy and often project-dependent. Therefore it is most of the time more useful to create far fewer diagrams manually, which will contain much more useful information.