TYPO3 is a free Open Source content management system for enterprise purposes

phpSupport is your customer friendly trouble ticket system

phpwcms is a robust and simple but yet powerful web based content management system

Vanilla Forums are open-source, standards-compliant, customizable discussion forums.

PhpWiki: a PHP WikiWikiWeb

Vtiger CRM is a free CRM software ideal for small and medium businesses, with low-cost product support available to production users that need reliable support.

Vty is a web-based database manager script written with Php. It's for Mysql.

Allows you to add free guestbook to your site

WebCalendar is a PHP-based calendar application

Piwigo is a photo gallery software for the web