Something that I've found myself wishing for time and time again is to be able to follow the link to a file and immediately pop into a set of M-x occur results given some search term for that file.  That way I could link to an overview of a file's class/function definitions, or config stanzas, or other useful things.  Given that we can create links to arbitrary elisp, I am sure that this can be done in principle, but if there's a quick recipe that someone has come up with, I'd love to hear about it!