Wolfram.com - Mathematica - Symbolic, graphics, language and numerical software. Page includes explanation and visual snapshots of program. - http://www.wolfram.com/
MathTensor, Inc. - Developers and distributors of MathTensor, a Mathematica-based package for performing tensor analysis by computer. Formerly MathSolutions, Inc. - http://smc.vnet.net/mathtensor.html
Scientific Arts - Consulting with Mathematica: Scientific Arts is a consulting and creative services company which provides targeted solutions for a broad range of scientific enterprises. - http://www.scientificarts.com/
HostSRV - A web hosting company dedicated to providing MathScript capabilities to websites. - http://www.hostsrv.com/
Analytica - Analytica provides consulting and training to the Mathematica community. - http://analytica.com.au/
MathC - MathC provides statistical consulting using Mathematica, visualization of mathematical concepts in the area of teaching Mathematics, and Mathematica-applied college-level mathematics. - http://www.mathematica.co.kr/