A virtual Internet OS with an XML runtime. It offers a microkernel modular component architecture and integrates a comprehensive set of XML technologies. It features an XML runtime, XML pipeline processes with loops and exception handling, virtualized modular URI address spaces, and a dependency-based cache."
abaXX elements is a full-fledged portal-building software including easy-to-use MVC support, a Portlet framework, an event model, a Portlet deployment model, a Struts compatibility option, a tag library, a set of web widgets (trees etc.), a ready-to-run 'vanilla' base portal, a rather amazing live web portal configurator ('PortalBuilder'), and plenty of professional documentation. The developer licence is free.
Project Able is a full Java-based web development stack designed to make web development painless. In a sense, it is an attempt to bring together quality opensource tools in one cohesive stack, similar to what Rails has done for Ruby, while also encouraging common practices I've used in software engineering for a long time.
Artifactory is a Maven2 proxy repository with advanced features. It is based on JCR (using JackRabbit as the implementation), with a web UI based on Wicket, and embeded Jetty for quick start. All artifacts are stored in an embedded Derby DB.
Atomic is an object environment that creates a virtual space in which Java objects can be created, linked and taught to relate to one another. Atomic uses technology found in neutral networks, databases and distributed systems. Atomic can be used as a stand-alone server, with integrated web, console and 3D GUI services. It can also be used as library within other products.
MIDAS Configurator is a web-based configuration and administration GUI for various network and system management suites, eg. for HP OpenView Operations for UNIX. MIDAS allows you to browse and change the complete configuration data by linking all related information together. Configuration items can be saved transparently in a version control system. MIDAS is based on an enterprise service bus (esb) and runs on HP-UX, Solaris, Linux and Windows Server operating systems.