FreeSB is a (service oriented) alternative to hub-and-spoke messaging, enabling new and legacy systems to plug in to the bus and communicate with other systems on it, thus providing loosely-coupled application integration. FreeSB is currently implemented in Java but ESB clients should be implementable in other languages (Python, .Net, etc.).
Roundhouse is a modular J2EE application platform that allows applications to combine Struts modules, JSR-168 portlets, and Web services into a single application. It is intended to take the drudgery out of new J2EE application development by providing existing user and security architecture, navigation, and logging although it can be used standalone with no additional development. It ships with forum and blog modules along with several handy portlets which essentially make it a a portal based blog and forums application. The architecture is Struts-based and includes a Struts-based JSR-168 Portlet container. Developers extend Roundhouse by creating new standalone modules which can be independently developed without mucking around in the Roundhouse codebase and merged with Roundhouse and any number of other modules at build time. Modules can be created, packaged as MARF files, and redistributed.
Apache Rivet is a system for creating dynamic Web content via a programming language integrated with Apache Web Server. It is designed to be fast, powerful and extensible, consume few system resources, be easy to learn, and to provide the user with a platform that can also be used for other programming tasks outside the web (GUIs, system administration tasks, text processing, database manipulation, XML, etc.). It is similar to PHP, except that it uses Tcl, and provides both HTML/Tcl pages as well as pure Tcl pages to aid the programmer in separating logic and presentation when necessary.
Spinneret is a structured storage engine that can be thought of as an extended tuple storage system. It takes the best aspects of relational, object, and hierarchical databases and throws away the dead weight associated with those technologies. The benefit of Spinneret is that its data model is incredibly flexible, allowing it to expose its underlying data in any number of ways. It operates similar to an object database, but without hard ties to an originating language, and can also behave like a relational database without the burden of complex joins.