Enzyme is an architecture for creating user-searching-user applications. Right now, it is primarily useful as a resume create/search and HR management system. However, it's potential uses are wide-ranging, and it offers PHP developers an alternative to relying on simple "keyword" searching systems.
XMLDB uses an RDBMS to persist arbitrary XML documents. Due to its storage mechanism, searching for and recalling documents is extremely quick. You can also perform XSL translation on documents with surprising speed. The library can be used in any program to store libxml2 documents. A PHP module is also included, making XMLDB into a complete three-tier Web application development suite.
GNU EPrints is a solution for sites wanting to set up archives. By default it is configured to be an archive of research publications but can be easily altered. It is scalable and robust; all metadata is stored in UTF-8 rather than ASCII, and all "phrases" the system uses in user interaction are stored in an XML file for easy editing or translating. The system is built around Apache, mod_perl, and MySQL. Submissions are made via the Web and not entered into the main archive until approved by an editor.
C-Cramp (the C-Cramp College Radio Audio Management Program) is a Web-based frontend to MySQL for managing the types of things that small radio stations might need: audio files, data, and "metadata"; DJ and staff information, schedules, live music and program logs, and all sorts of other data. Currently, a cross-platform PHP application is the focus of the project, but more features and types of programs are planned that will hopefully enable easier playback, storage, loading, and entering for all types of applicable data.
xmltvdb creates a database from a set of xmltv listings and then provides a Web interface to view the TV listings in a grid format similar to many Web-based listings providers, but with user customization and no advertising. It supports explicit and bayesian classification of shows to highlight items you like and de-emphasize ones you don't.