yEd is a powerful graph editor that is written entirely in the Java programming language. It can be used to quickly generate drawings and apply automatic layouts to all kinds of diagrams and networks.
ThinkUI SQL Client is designed for Java™ developers who needs to work with multiple databases and would like to a tool with features that will improve their productivity and help reduce the tedious nature of software development.
RaVeR (See the Music!) is a sound animation program. It renders full screen 3D animations in synchronization of music or any kind of sound at realtime! It is open source, free, works in Linux using ALSA and OpenGL. (old SDL and SVGALib versions avail.)