Chris Oliver, who works at SeeBeyond, that is now Sun Microsystems, showed us, while I was at Sun, F3 a programming language he was working on. Apparently F3 will soon be open sourced on java.net. That is great news!
F3 is a declarative language that makes the creation of Swing UIs a lot easier. Take a look at the examples Chris has posted on his blog to get a better idea of what you can do with it. If I remember correctly the other examples Chris showed me like a year ago, you can also put real Java code in there. I know that Chris has writtent many impressive demos that showcase the power of his tool, that's why I really advise you to keep a eye on java.net and F3.