What tools are available for creating UML Class Diagrams from a set of .h- or .cpp-files?
I am looking for something that...
You can try ArgoUML which is free, has a nice GUI and is written in Java so can be run painless on any system.
It is able to generate C++ from UML diagrams; however, reverse engineering of C++ source code is handled by a sub-project for the moment. The latest snapshot of this tool can be downloaded from the source repository. Yet, this tool is still in development, so it might not work as you would expect.