I often find that the headers section of a file gets larger and larger all the time, but it never gets smaller. Throughout the life of a source file, classes may have moved and been refactored and it's very possible that there are quite a few #includes that don't need to be there and anymore. Leaving them there only prolong the compile time and adds unnecessary compilation dependencies. Trying to figure out which are still needed can be quite tedious.
Is there some kind of tool that can detect superfluous #include directives and suggest which ones I can safely remove?
Does lint do this maybe?
It's not automatic, but Doxygen will produce dependency diagrams for #included files. You will have to go through them visually, but they can be very useful for getting a picture of what is using what.