BlueJ is downloadable software that  provides an easy-to-use teaching environment for the Java language to help teach beginning Java programmers.  It uses visualization and interaction techniques to create a highly interactive environment that encourages experimentation and exploration. BlueJ is based on the Blue system developed in Australia at the University of Sydney and Monash University.

On this site, your can download the software, link to extensions, and review documentation.  There is also an FAQ, weekly tips, a discussion forum, and links to other Java resources.