Mathematical Programming Languages

R / S+ for statistical computing

Other stat languages: SAS, SPSS, STATA, GAUSS, etc.

Octave, an open source clone of Matlab

Fortress, "a language for high-performance computation that provides abstraction and type safety on par with modern programming language principles."

Maple

Maxima

R, Numpy/scipy for Python, Maple, Yacas, even Fortran.

There's always APL, with its builtin matrix operators. Modern APL even supports .NET.