There have been a lot of AJAX discussions in this forum lately. See
here, for example. I've used it to turn an existing
applet demo into a very similar demo in which the
Java code runs on the server and the GUI runs in the browser. I think it's very cool. Is it a fad? Not so much, really; the underlying ideas and tecnologies have already been around for a while and are used quite broadly; just the buzzword -- and the range of exciting applications -- is new.