ICEfaces is a set of AJAX components for JSF. As of this writing, they are currently in Alpha. In testing, I found it to be quite good. I haven’t been able to test it in a production environment yet, due to its early state, but I imagine I will be using it in the future.

One concern that I know they are working on is the server overhead that will result from using ICEfaces. To the best of my current knowledge, the entire tree must be rebuilt with every call. It performed excellently in a test environment, but I imagine that would change with several hundred simultaneous users.

It is worth checking out. You can see examples of the components here.