graphviz

graphviz is a set of graph drawing tools and libraries. It supports hierarchical and mass-spring drawings; although the tools are scalable, their emphasis is on making very good drawings of reasonably-sized graphs. Package components include batch layout filters and interactive editors for X11, Java, and a TCL/tk extension. The batch filters can be configured as a web visualization service (using GIF and click-maps). Typical applications include display of finite state machines, software diagrams, database schemas, and communication networks.