d33n

There are a lot of open source products you can use, I would advise start at http://en.wikipedia.org/wiki/List_of_content_management_syst... to find a Wiki/CMS in the language you like most, with a flat-file database. Then look for plugins/extensions that provide the community features you need.

and in combination with nknighthb's comment you get this: http://www.rikeripsum.com/