I need an odd little piece of software that I'm certain is somewhere out there, but I can't figure out the right search terms to find it. I have a nice 2D graph showing a bunch of labeled circles connected by arrows. Computer scientists call it a "directed graph". It's just circles and arrows. However, it has grown so big and complicated that I'd like to shift to a 3D display, in which I can reposition spheres and add one-way links between them, and add new spheres. I have seen such displays before (there's one that shows the connections between any one website and all that link to it), and I know that they're simple to program, so I'm sure that there's a program out there for doing it. Can anybody direct me to such a program? Failing that, could somebody educate me as to the terminology used to describe such a program -- I could use such terms to find something.