Let your clients take some of the load off your webapp server... also:
Feature Article: An (Almost) CPU-Free MVC Pattern with Ajax
Java Today: GNU Classpath / OpenJDK hybrids, Jersey project, and Java Mobility Podcast #9
Weblogs: Clarifying the pauseApp() deprecation proposal, ode to Opera Mini, and Hello JPA World
Forum Posts: More on OS-specific features, version-based web start, and searching for objects in unmarshalled XML