Omeka is a free, flexible, and open source web-publishing platform for the display of library, museum, archives, and scholarly collections and exhibitions. Its five-minute setup makes launching an online archive or exhibition as easy as launching a blog.
The DBacesslayer aka DBSlayer aka Släyer is a lightweight database abstraction layer suitable for high-load websites where you need the scalable advantages of connection pooling. Written in C for speed, DBSlayer talks to clients via JSON over HTTP
Open-source server application packages for deployment as appliances (e.g., virtual machines) or sandboxed local installation on Linux, OS X, or Windows. Smaller application downloads are available to pair with LAMP, LAPP, and Ruby base stacks. Handy for test-driving applications.
A free (libre), open-source (GNU GPL), content management platform designed for group collaboration. Open Atrium is based on Drupal (running on Apache, with a MySQL database).