PHP On Pie is a PHP framework that combines the best ideas from PHP projects like Drupal, CodeIgniter, Kohana, and ZendFramework. It has very few core concepts: classes, models, events, slots, and tools. It lets you repackage completed apps into plugins that you or others can use later. Its smart database classes allow you to implement vertical and horizontal partitioning (sharding) easily to handle millions of users.
Open School Admin (OSA) is a Web-based school administration system primarily focused on ease of use and access to school information. It has been in continuous use and development for the past 7 years. It manages all aspects of school administration: student enrollment, class scheduling, mark reporting, attendance, user accounts, and room booking. Through the use of various plugins, it also manages email announcements (including automated attendance notices), government reporting, dorm room management, Alumni relations, etc. It is a standalone application written using a Perl/MySQL back end. It requires a Web server (Apache/Lighttpd tested) and should run out of the box on any Unix system. While OSA itself is very mature, the installation and setup is still a young and evolving process.