ExplicitLayout layout manager (Commercial) and EventInitializer to replace your anonymous inner classes (BSD).

Utility class libraries: VMMemoryWatcher library that visually track memory changes in Java Virtual Machine; Flow monitor library that visually track process flow between containers. [Open source]

For generating images on servers, without the need for an X server. [Open Source, GPL]

Various graph-drawing and traversal algorithms. Support for user interaction such as adding and removing vertices. [Open Source, GPL]

Offers various class libraries including "JetChart Library", which displays a variety of types of charts. [Commercial]

A library for graphs, diagrams and networks, with an option for automatic layout by Northwoods Software. [Commercial]

A Swing component for displaying vector graphics and animation. It can deal efficiently with very large vector images e.g. geographic maps or electronic circuits.

Java GTK+ and Gnome bindings using JNI. [Open Source, LGPL]

Applets, beans and applications. [Freeware]

Manipulation methods for inversion, rotation, shifting, adding, loading, saving and creating images. (Open Source)