From the official AssoCIateD website

AssoCIateD (ACID) is a simple PHP CMS which was initially thought for an association (http://acabe.ecu.free.fr) but grew because of several demands.
lets users understand how the application works
AssoCIateD was at first designed for a Capoeira association named ACABE. The main goal was to provide the association a simple way to maintain its website, by letting active users the possibility to update the site (add articles, medias, news, events...), and this way make the administrator's work easier.
It was initially thought to be simple, monolithic, but with time and functions addings, it grew and became interesting for any other people that wanted
to gather those functions in only one application.

Indeed, as lots of open source application only provide one point of view, and deepen mainly one functionnality, problems come when users want to add other features to their site, those features being present on other applications, but not in the one they initially chose. At this time there are galleries, there are blog managers, there are calendars, in a huge amount.
I don't have the claim to make better than those applications' programmers, but, AssoCIateD give the minimum of features in all of those perspectives, in an application much easier to install and to use than a portal or other (powerful) a

Download:http://sourceforge.net/project/showfiles.php?group_id=162599
Demo:http://herve.labas.free.fr/demo/