Sage is Awesome!

I just started playing around with Sage this morning and am already hooked!  The pedagogic possibilities alone would make learning to use Sage worthwhile for economists...imagine a classroom where the lecturer was simultaneously plotting production possibility sets in 3D and then manipulating them as she chatted about returns to scale, diminishing marginal products, sunk costs, etc.

On the research end, Sage has most (if not all) of the functionality of MatLab, Mathematica, Magma, etc and because it is Python based it incorporates a large number of additional features absent from those other platforms...and it is totally free!