JGraph is a free, mature, and robust Java diagramming library. It contains all the graph visualization, layout, and interaction functionality you might expect in a graph library, including multiple views, layering, zoom, drag and drop, undo, automatic expanding and collapsing, routing, and layouts. You can create workflow editors, BPMN, CAD tools, network diagrams, database visualization tools, and more. It is fully documented, including examples, and has an active support community.
QCad is a powerful but easy to use 2D CAD program for Linux, Windows, and Mac OS X. It uses DXF as its standard file format. While other CAD packages are often rather complicated to use, QCad tries to stay comfortable, and even an absolute beginner can create professional drawings with a minimum of effort.
V_Sim visualizes atomic structures such as crystals, grain boundaries, molecules, and so on It can work with files either in binary format or in plain text format. The rendering is done in pseudo-3D with colored spheres to represent the atoms. The user can interact through many functions to choose the view, the size of the atoms, their color, the background color, the type of fog, and more. Moreover, V_Sim allows you to export the view as images in GIF, PS, and other formats.
BNNS is a research tool for interactive training of artificial neural networks based on the Response Function Plots visualization method. It enables users to simulate, visualize, and interact in the learning process of a Multi-Layer Perceptron (MLP) on tasks that have a 2D character. Tasks include the famous two-spirals task or classification of satellite image data.