HyperPhysics is an exploration environment for concepts in physics which employs concept maps and other linking strategies to facilitate smooth navigation. For the most part, it is laid out in small segments or "cards", true to its original development in HyperCard. The entire environment is interconnected with thousands of links, reminiscent of a neural network.
This site for learning Physics concepts employs undirected graphs for navigation. Its a perfect example of how various types of dot-graphs can be used to convey the same information as a "list" or "outline" only with far more context.