Online journals, libraries, databases, etc.

MathSciNet Search
UofM Libraries
History of Approximation Theory (HAT)
Surveys in Approximation Theory (SAT)
Mathematics Journals at JSTOR:
American Journal of Mathematics; American Mathematical Monthly; Annals of Mathematics; Journal of the American Mathematical Society; Mathematics of Computation; Proceedings of AMS; SIAM Journal on Applied Mathematics; SIAM Journal on Numerical Analysis; SIAM Review; Transactions of AMS
SIAM Journals Online

Miscellaneous links

Math websites around the world
The Prime Pages
MathWorks (MATLAB)
MathSoft (Mathcad)
History of Math
Journal of Approximation Theory (by Paul Nevai)
Science Magazine