(Diver is in the process of being moved to GitHub. Please find us at https://github.com/thechiselgroup/Diver. Support requests & messages sent here may never be seen.)
Dynamic Interactive Views For Reverse Engineering. Div/er is a set of Eclipse Plugins that aid developers in understanding software. It uses dynamic analysis and reverse engineering to offer views and filters that aid comprehension and discovery.
Swing Spy is java based Swing/AWT spy agent that prints the widget under the cursor (like Spy++ for Windows/MFC and SWT Spy for Java-SWT). Download from the homepage: http://www.nenoff.com/swingspy/