OpenGL question (not game programming)

I have recently implemented a real time 3-D visualization program for my current project. It animates the crystallization of various simulated systems. Now, however, I would like to generate movie files, preferably MPEG for presentation purposes and I was wondering what the easy way to go about this was. Are there any tool kits available which could make my life easier in the conversion department? By the way I am using gcc under lunix, and I wrote the program using openGL and glut.