Phpnuke

Phpnuke is a web based automated news system. The administrator has total control of his web site, registered users, and he will have in the hand a powerful assembly of tools to maintain an active and 100% interactive web site using MySQL databases.

The system is written in PHP and has been released under the GNU Public Licence.

Links:
http://www.phpnuke.org/
http://nukeaddon.com/
http://www.bomis.com/rings/phpnuke/