Wondering if there's anything along the lines of a "file cabinet" plugin that can limit access by user permissions?
For example, something "PHP Advanced Transfer Manager" as seen here: http://www.avlogicsfileserver.com/ - where files can be categorized and such, and access controlled based on existing site permissions - ie. public access some folders, "Subscribers" can access those and certain others, "Authors" can access yet another set of folders, etc.
I found "EHT Downloads", which creates a fully-expanded tree of the entire selected folder (which is very messy), but appears to be abandoned. I haven't been able to find anything else, at least not with the search terms I've been using.