Khan Academy is a free website that strives to offer a world-class education to anyone and allows users to work at their own pace. KA offers videos, exercises, and tests from basic elementary math through and beyond calculus, as well as on a variety of other topics. Sign up for a free account and it will track your progress and provide personal statistics.
Want to watch Khan Academy videos offline or on-the-go? The iPad/iPhone app for Khan Academy can be found here:
Mathematical Association of America
The Mathematical Association of America is the largest professional society that focuses on mathematics accessible at the undergraduate level. Members include university, college, and high school teachers; graduate and undergraduate students; pure and applied mathematicians; computer scientists; statisticians; and many others in academia, government, business, and industry. The mission of the MAA is "to advance the mathematical sciences, especially at the collegiate level."