I think Netbeans is a pretty good Java IDE from a first glance. But it is really a whole lot more than just Java. It is packed , without being bloated can you say WebSphere, with features. One of the cool features is the XML schema designer.
Check this out -
Notice the Selected Design Pattern: Venetian Blind. This is pretty cool. It will apply the design pattern to whatever XML schema you currently have it in. It supports Salami Slice, Venetian Blind, Garden of Eden (New to me) and Russian Doll.
Of course the tool has about a million other features as well including a pretty nice UML tool. I don't want anyone to think I've done any kind of serious evaluation on this but at first glance it is promising. And of course it is free from Sun like most of their software these days.