I agree that proprietary software is a significant barrier to the diffusion of this approach. E-views is bad enough but my god, MODLER! (there has to be a story there). R is a good candidate, especially since many learnt it in stats. Octave is an open source clone of matlab … but I don’t like it. Neither of these are particularly ‘nice’ languages. I’d suggest looking at Python. It’s open source and far more intuitive than the other two. InsightMaker is a cute program I once built SIM on. Its far to limited to do anything else, but it might have some pedagogical use. Translators are an interesting idea but may or may not violate terms of service.