The igraphics lisp package allows the user to write postscript files from common lisp, which can be printed directly or read into the Interviews idraw drawing program for editing. These files can also be read by Adobe Illustrator 6.0 using the postscript parser. The lisp code is simple and easily modifiable and extendible. I've used this code extensively to plot data and show moving objects. The ability to read the file into idraw makes it easy to annotate the plots.
You need the following files: