Apache Wicket
Apache Wicket is a Web application framework written in Java. Wicket is a component based development framwork. Wicket provides transparent state management and Wicket pages can be edited using HTML authoring tools. There are no XML configuration files (no XML is becoming a feature these days!) and all processing is done in Java.
Wicket promotes separation of concerns and Java properties and HTML markup is associated using Wicket ids. Wicket also provides transparent clustering support. Wicket also provides a set of re-usable components such as Pageable ListView and Tree component.