SAGE: Software for Algegbra and Geometry Experimentation
SAGE is free and open software that supports research and teaching in algebra, geometry, number theory, cryptography, and related areas. Both the SAGE development model and the technology in SAGE itself is distinguished by an extremely strong emphasis on openness, community, cooperation, and collaboration: we are building the car, not reinventing the wheel. Our overall goal is to create a viable free open source alternative to Maple, Mathematica, Magma, and MATLAB.Nifty. A practical application? Math server, says Steve Hastings via Pournell's Chaos Manor
I suggested that they should make a bootable CD image that runs SAGE in web-server mode. You could take any spare PC, boot from the CD, and your network now would have a SAGE server. I can imagine that being very popular in schools.I can imagine it being popular elsewhere - any company that uses Mathematica can likely use a tool like this. You can't beat the price.