Google Web Toolkit - join
The official Google Web Toolkit (GWT) developer discussion group. GWT lets you build AJAX apps in the Java programming language.
Low activity, 19772 members, restricted

JSR-305: Annotations for Software Defect Detection - join
Discussion of JSR-305 in the Java community process, and effort to develop standard annotations that can be interpreted by tools to assist in software defect detection.
Low activity, 106 members, restricted

NetBeans - join
This is a group for all NetBeans users
Low activity, 282 members, restricted