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JSF (JSR 127) is a standard Java EE specification of a component based web application framework for developing user interfaces.

JSF uses JavaServer Pages (JSP) for its default display technology but can also integrate other technologies (such as Facelets).

The JSF framework provides a set of APIs for representing UI components, managing their state, handling events and input validations and defining page navigation.

Upcoming JSF 2.0 will provide new improvements and features such as integrated AJAX, templates, annotations and more.

With proper mark-up/logic separation, a POJO data model, and a refreshing lack of XML, Apache Wicket makes developing web-apps simple and enjoyable again. 
Write UI in Java as you would for your desktop, write (and preview) HTML without any special characters, embed AJAX as simple Java callbacks, simply put – write web UI as you always wanted to. No wonder everybody loves Wicket. 
And yes, it has no XML configuration. At all.

Struts2, the popular MVC framework, has roots back to 2000. 
Struts2 is based upon a POJO action model with a simple, flexible architecture using plug-ins and introducing DI and interceptors. 
Struts2 incorporates a rich, customizable (UI/Ajax) tag library. 
Struts2 supports many view technologies and has expressive validation support. 
Struts2 has strong synergy with Spring framework and several other open source frameworks and projects.

By compiling your Java code into Javascript, GWT effectively eliminates the boundaries between the client and the server-side. 2 years after the initial GWT release, hundreds of components are readily available, all accessible with a swing-like Java API. GWT focuses on dynamic Ajax applications while not forcing you to resort to Javascript. It emits highly optimized Javascript code and provides a very efficient serialization mechanism between Java and Javascript. It ensures your application remains cross-browser compatible, allows easy integration with 3rd party Java and Javascript libraries, and provides testing and debugging tools.

Spring framework's own web framework. Spring Web MVC framework is a robust, highly flexible web framework built around the MVC design pattern. 
Spring Web MVC offers clear separation of roles, integration with many view technologies, strong REST foundations and much more. 
Together with Spring web flow, Spring Web MVC provides a strong foundation for a full-stack web framework.