If some of you are interested in mathmatics, here is a good piece of software from 1991: RIEMANN.
- perform algebraic calculations (factor, expand, integrate...)
- draw 2D or 3D graphs
- load save programs with its own very powerful language
- export formulas to LaTeX files
- export graphs to Metafile
It was only in German and I made the english translation.
If you want to learn more about it: