Popular web-based bug tracking system. It's lightweight and easy to use and deploy.
Dolibarr ERP & CRM is a software to manage small or medium companies, freelancers or foundations.
A web-based interface for system administration. Using any modern web browser,advanced users can setup user accounts, Apache, DNS, file sharing and removes the need to manually edit Unix configuration files.
Usermin is a web-based interface for webmail, password changing, mail filters, fetchmail and much more.
Originally written for Wikipedia. It is now used by several other projects of the non-profit Wikimedia Foundation and by many other wikis.
GLPI is the Information Resource-Manager with an additional Administration- Interface.