Some kind of wiki
wouldn't require a lot of external help, I guess.
I myself use a fork based on an ancient portal solution : php-nuke (see it in action here
). It's a feature full portal, excellent at displaying "stuff" (articles, downloads...) in an standardized manner... once you get the hang of it. Well, that would probably be overkill. But if people aren't put off by its sheer ugliness, I would gladly expand my "download pad" with an Amiga manuals section, depending on what suits you best of course.
Note that some of the downloadable archives present on it may be in a grey zone area in terms of copyright compliance