Nifty GUI Editor Project

There is a Nifty editor project started by Cristiano Aguzzi which looks very promising. It allows you to create Nifty GUI XML by simply adding Nifty Elements and Controls with drag'n'drop!

http://niftyguieditor.altervista.org/</a></p>

It's a Java Swing application that uses the Nifty Java2D renderer for preview. This means you can change Element properties and see the changes in realtime! Pretty, erm, Nifty! :D