Web Resources in mathematics:
The Electronic Library of Mathematics: Mathematical Journals (EMIS)
ViFaMath : The virtual library of mathematics.
Softwares:
Mathematica / Wolfram Research
Macaulay2 / A software system for research in Algebraic Geometry
Macaulay2Web / Macaulay2 Web Interface
Julia / Programming language
HomotopyContinuation.jl / Julia package for solving Systems of Polynomials
Oscar.jl / Algebra Software
Python / Programming language
Matlab / Programming language
Guides to Resources in specific topics:
DS Web: The dynamical systems web / SIAM.
Number Theory Web / Keith Matthews, Dept of Mathematics, University of Queensland, Brisbane, Australia
Topology Atlas: Information related to topology.
Employment & careers
Mathematical sciences career information / AMS-MAA-SIAM - Project for Non-Academic Employment
History of mathematics & biographies
ChronoMath: une chronologie des mathematiques / Serge Mehl.
History of Mathematics / Maintained by David E. Joyce, Clark University.
The History of Mathematics / David R. Wilkins, Trinity College, Dublin.
Selected mathematicians and statisticians / InfoPlease biographies
Biographies of women mathematicians / Agnes Scott College, Atlanta, Georgia.
Comparative Prices of Math Journals
Comparative prices of math journals 1997 (2000 update) / Professor Rob Kirby, University of California, Berkeley.