The MySQL database server is the world´s most popular open source database. Over six million installations use MySQL to power high-volume Web sites and other critical business systems.

phpMyAdmin is a tool written in PHP intended to handle the administration of MySQL over the Web.

The Apache project is an effort to develop and maintain an open-source HTTP server for various modern desktop and server operating systems, such as UNIX and Windows NT.

WordPress is a free and useful state-of-the-art semantic personal publishing platform with a focus on aesthetics, web standards, and usability. What a mouthful. WordPress is both free and priceless at the same time.