Math
Mathematics is a language. (J. Willard Gibbs at a Yale faculty meeting)
General Resources/References
MathWorld from Wolfram Research
Abramowitz and Stegun: Handbook of Mathematical Functions pdf link to tar file
Numerical Recipes online books
Practice Exams
Mathematics Department, Brooklyn College
Reviews
MIT Professor Kleitman: Calculus for Beginners and Artists, including flash animations
Practical Calculus Review
Calculus
Multivariate Calculus
Interactive/Software/Web Resources
Applets for Online Instruction in Math and Physics
Web-Based Quantum Mechanics Course (go to Module list for specific topic reviews)
Mathematics page at Frank Potter's Science Gems pretty extensive collection of links to miscellanea, such as
Extensive collection of Maple worksheet demos
School_of_Mathematics Wikiversity School of Mathematics
Recommended Textbooks
Stewart, James. Calculus. 8th Edition. Cengage Learning, 2016. ISBN: 1285740629, 9781285740621
Poole, David. Linear Algebra: A Modern Introduction. 4th Edition. Cengage Learning, 2014. ISBN: 1285463242, 9781285463247.