Scientific Spreadsheets (Score 3, Informative)

You want a program like Origin -- a spreadsheet designed for scientific computing. While it's both very much not free and windows only, sometimes you just have to use the right tools for the job. A free or even just Un*x friendly replacement for Origin at its level of sophistication would be a very Good Thing. I'm hoping that there are other, similar software packages out there, but that's the one I'm most familiar with.