An open source Java IDE formerly owned by IBM. It is written in SWT which provides a faster native GUI than other Java IDEs like NetBeans and JBuilder. Its refactoring utilitiy is superior among other IDEs as well. 

It has many plug-ins available for free download or buy, for different purposes from Swing/SWT GUI building to UML modeling, for example [SWT GUI Builder|], [JBeaver Swing GUI Builder|], [SDE for Eclipse|SmartDevelopmentEnvironment].