I figure most of us name our code packages like:
This causes a lot of empty directories ("com", and "mycompany" I'd rather not look at in the project browser.
The IDEA flatten directories feature is great, but I think we could go further and specify specific directories to omit from this list. (The exclude feature won't work, because we still want to show the subdirectories).
IDEA could allow us to set this explicitly, or perhaps detect empty directories and have an option to omit those (of course, my directories are not strictly empty, but have a "CVS" subdirectory, so it'd have to be smart about still considering them empty).