Apache Click is a modern JEE Web application framework, providing a natural rich client style programming model. Apache Click is designed to be very easy to learn and use, with developers getting up and running within a day. It also supports automatic component rendering, client/server side validation, full localization, and multiple template engines (currently Velocity, JSP, and FreeMarker).
Ontopia is a set of tools for building applications driven by Topic Maps, such as Web portals. The main benefit of Topic Maps is that they provide a flexible and expressive data model supporting much better findability than traditional solutions, as well as advanced features like automated merging of datasets.
VRaptor3 is a fully-fledged Java Web framework focused on fast development and maintainable code. It intends to make RESTful application development easy. A resource corresponds to a business logic annotated with its path and HTTP method. It runs inside DI Containers (Spring or Pico out of the box) and, therefore, enables full integration with them. Also, using Hibernate is easier: its session is automatically injected by VRaptor, so you just have to use it. VRaptor3 is refactor-friendly, especially in its redirecting configuration. It is also nicely extensible.