ICEFaces

Last year I used a tool called ICEFaces to create an AJAX web application.
It was pretty cool. Here are some of the features and advantages that led us
to choose ICEFaces:

• Component-based AJAX/RIA/Web 2.0 framework.
• JSF-compatible.
  
• All Javascript is behind the scenes.
• Client footprint is lighter than other AJAX frameworks because most processing is handled on the server. All the client does is process updates.
• Security: no application specific Javascript is published to the client.
• Free/Open Source Software.
• Good online documentation.
• Active and helpful forum.

Several developers who had used JSF before but with no knowledge of
Javascript or AJAX were able to quickly come up to speed using ICEFaces,
because it functions as a JSF component library. Once you get the
ICEFaces configuration set up you can just drop in components.