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.
Invenio (formerly CDSware) is a suite of applications that provides the framework and tools for building and managing an autonomous digital library server. It complies with the Open Archives Initiative metadata harvesting protocol (OAI-PMH) and uses MARC 21 as its underlying bibliographic standard. Its flexibility and performance make it a comprehensive solution for the management of document repositories of moderate to large size.
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.
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.