WindowBuilder is a powerful and easy to use bi-directional
Java GUI designer that makes it very easy to create Java GUI
applications without spending a lot of time writing code to
display simple forms. With WindowBuilder you can create
complicated windows in minutes. Use the visual designer and
Java code will be generated for you. You can easily add controls
using drag-and-drop, add event handlers to your controls, change
various properties of controls using a property editor,
internationalize your app and much more.

WWW: http://www.eclipse.org/windowbuilder/