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.
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.
libphidgets is a user-space access library for the Phidget devices. It provides a generic and flexible way to access and interact with the Phidgets, and comes with all the advantages of a user-space library. It is based on libhid (which is based on libusb), thus it requires no HID support in the kernel. Furthermore, it aims to support all operating system supported by libusb/libhid: Linux, BSD, OS X, and Windows.