Check out Everything. :)
in reply to Is there an off-the-shelf Online Membership solution?
If you want other GPL software, there's
Yet Another Web Portal System, and its derivatives
Poas. Out of these three WebApp seems to have the largest user base, and it has a semi-automatic install script.
You can also take a look in CGI Resources Directories and Portals and CGI Expo Portal Scripts for other community portal scripts.
Most of these are complete member site applications encompassing multiple scripts. If you just want some perl scripts that you can use to put together your own flavor of community check out Extropia.com for several open source web apps you can use for your site.
P.S. YAWPS, WebAPP, and POAS are all 100% Perl with no DB required.