Java UI Toolkits (for the Web)
One thing that was big at JAX were these toolkits that allow Java developers to program user interfaces the way they're used to, by using libraries similar to SWT or Swing.
Two big ones I saw were Rich AJAX Platform (RAP), based on SWT, and wingS, based on Swing.
Now, Google has released the Google Web Toolkit (GWT). Not tightly based on a previous Java UI framework, GWT seems to be another good option for developing complex web user interfaces in Java.