Software useful for Mathematician, Teachers, Research students, Technical book authors.

• LaTeX Mathematical Documentation System

School level software

• Dr Geo Geometric Figures

Software for Under graduate and higher maths

• Sci-lab Linear Algebra, Calculus
• Maxima
• Euler Numerical Programming

Research level Free Maths Software

• Singular A Computer Algebra System
• Macaulay 2 is a software system devoted to supporting research in
  algebraic geometry and commutative algebra algebraic geometry and commutative algebra
• Cocoa Computations in Commutative Algebra
• Kash/Kant Computational Algebraic Number Theory
• Polymake
• CaTS

General Graphics Software

• POVRay Ray tracing Graphical Free software