Project Euler for programming problems.:  "Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems."

I was looking up V=IR, P=IV, etc…  and found this site:  Equation Sheet site.  It has algebra, calculus, statistics, and physics, etc… equations.

A simple AJAX TODO List and links to the code