The Widget Jones Library is a lightweight, flexible, template-driven widget build system. It is intended to simplify creating portable widgets. Write your code once, build it with WJL, then run it on several widget platforms like Apple Dashboard, Windows Vista Sidebar, iGoogle, and more.
XUI is a Java and XML platform for building Rich Internet Applications. The platform greatly reduces the amount of code needed to build feature rich applications on a wide range of systems. The project includes plug-ins for both NetBeans and Eclipse, plus support for AWT, Swing, SWT, J#, and HTML.