I am pretty amazed with the Processing project. It's a full-blown, java-based programming language which has added commands to generate 3D graphs. I played around with it and pretty quickly built a tool which plots 3D coordinates which are stored in a file, onto the screen. It's fully animated, interactive, etc. The real killer is that the tool will generate a JAR with the entire code executable on Linux or Windows OR as an applet. Really worth having a look at!