The MathForge Application Environment provides users a broad range of Java-based math tools (calculation, visualization, presentation and communication via MathML) and allows developers to leverage existing code while extending MathForge.
Jtrix is a technology to allow code to be mobile, adaptive, distributed and scalable. Please see http://www.jtrix.org for much more documentation and info.
Labrador is an open source Web Services Hub written in Java. It is based on an incredibly simple, yet modular architecture, and attempts to transparently support the SOAP, XML-RPC, and REST protocols.