Agora is a Web-based, threaded discussion tool, similar to Usenet newsgroups. Agora remembers each user's preferences, and allows threaded, unread-only browsing. It offers the ability to manage several different groups, with different themes, forums, and administrators for each group. Agora offers a basic Web-based ICQ client, as well as a Web-based notes system.
Ariadne is a Web Application Framework and Content Management System built with PHP. It allows you to build complex Web applications and sites with ease. It takes care of the mundane stuff like internationalization, security, user management, templating, data retrieval and storage, caching, and site management. It stores content in a structured object store that can be accessed through an extensive filesystem-like API.
Cascade is a Web-based content management system. It's based around the idea of organizing resources into a hierachy of categories, much like Yahoo. Some features include generating static or dynamic HTML, allowing user comments on ratings on resources, design abstraction through templates, suggested addition and update management, an auto-generated "What's New" page, support for related categories and virtual subcategories, and more. It can use Postgres or MySQL as its SQL database.
DBPrism is an open source framework to generate dynamic XML from a database. It connects Oracle databases with Apache Cocoon, providing a high performance DBGenerator with functionality such as parallel content aggregation and ESI cache protocol. It also includes a powerlful database oriented CMS built on top of Apache Cocoon2 and DBPrism.
DB_Browser is a CGI tool for developers working with any relational database supported by Perl::DBI. It easily facilitates searching, editing, and adding to tables within a database. While it can be used as a regular interface to database data itself, it works well as a supplemental tool for developers creating their own primary interface.
OpenACS (Open Architecture Community System) is a mature toolkit for building scalable, community-oriented Web applications. Significant functionality is built-in, including user management, user group management, permissions, discussion forums, FAQ management, e-commerce, file storage, content management, and more. OpenACS is the foundation for many products and Web sites, including the .LRN e-learning platform.