WindowBuilder Pro

http://www.eclipse.org/windowbuilder/download.php

Installing WindowBuilder Pro

All downloads are provided under the terms and conditions of the Eclipse Foundation Software User Agreement unless otherwise specified.

Develop Java graphical user interfaces in minutes for Swing, SWT, RCP and XWT with WindowBuilder Pro’s WYSIWYG, drag-and-drop interface. Use wizards, editors and intelligent layout assist to automatically generate clean Java code, with the visual design and source always in sync.

These instructions assume that you have already installed some flavor of Eclipse. If you have not, Eclipse can be downloaded from http://www.eclipse.org/downloads/. Instructions and system requirements for installing WindowBuilder can be found here.
Update Sites
Eclipse Version Release Version Integration Version
Update Site Zipped Update Site Update Site Zipped Update Site
3.7 (Indigo) link link(MD5 Hash) link link(MD5 Hash)
3.6 (Helios) link link(MD5 Hash) link link(MD5 Hash)
3.5 (Galileo) link link(MD5 Hash) link link(MD5 Hash)
3.4 (Ganymede) link link(MD5 Hash) link link(MD5 Hash)

http://download.eclipse.org/windowbuilder/WB/integration/WB_v1.0.0_UpdateSite_for_Eclipse3.6.zip