Java Web MVC frameworks

My preferred framework is Spring MVC; it is a clean, simple request reply framework, though it does have its drawbacks.

Pure HTML frameworks

I am interested in the more exotic Java Web Frameworks like Wicket which enforce a "pure HTML" environment which makes collaboration between developers and designers easier.

JSF

The best thing about Wicket and Tapestry is that they are gradually moving the "standard" JSF framework in the right direction. Facelets.

WebServices

With the advent of Ajax, I suspect that the emphasis will shift away from server side MVC frameworks to browser based MVC frameworks that interact with Web services.