Cut The Knot! - This site focuses on problem-solving techniques, and includes solutions to a number
of intricate problems.

QuickMath - An automated service that gives immediate answers to various kinds of algebraic
and symbolic problems.

WebMath - Automated answers in many categories up through calculus. Includes compound interest.
Interesting site because the automated answer not only gives you the answer but shows
step by step how to get it.

Eric Weisstein's World of Mathematics - Online math encyclopedia. An excellent resource for looking up words and concepts;
often goes into a great deal of detail on the math involved. Try this one first!

Women Mathematicians - Biographies of women mathematicians, written by students at Agnes Scott College.
Includes many contemporary mathematicians.

MathGV - Free function graphing program for Windows.

Plotting Software - Free downloadable software for differential equations, statistics, geometry (2
and 3-D), plotting, voting methods, network analysis, games, linear algebra and more!

In Discovery or Inquiry-Based Learning, you are lead to discover the answer for yourself.
Read more about this method here.

Discovery Learning Project - Two sites in one! The Discovery Learning Project tracks various projects that use
and encourage the use of discovery methods. The Legacy of R. L. Moore site traces
the influence of Robert Lee Moore (1882-1974), a famous proponent and practitioner
of discovery methods of teaching.

Personal experiences with discovery learning methods - Everyone who teaches by discovery or inquiry-based methods does it a little differently.
This page (part of the Legacy of R. L. Moore site) contains about 30 short notes online
and references to about 30 more. Teachers give their experiences using these methods
and their impressions of their own teachers who used the methods.

Creative Teaching: The Heritage of R. L. Moore - A book-length biography and study of R. L. Moore and the "Moore method" of discovery
learning. Originally published as a print book by the University of Houston in 1972,
now available online in several digital formats.

SOS Math - Lots of good explanations, examples, and drills. Especially good on fractions
and polynomials. Covers algebra, trigonometry, calculus, and several advanced math
areas.

Math.com Algebra Worksheets - Generates worksheets with algebra problems. (No answers
though, so you'll have to check your work yourself.)

A+ Math - Mostly arithmetic. Has flashcards, games, worksheets.

MathStories.com - Hundreds of story problems with answers. Elementary school level.

Complex, Technology Based Problems in Calculus - These problems have a higher level
of complexity than traditional text book problems and foster use of a computer algebra
system. Each problem set includes discussions of related teaching issues and solutions worked
in Mathematica.

For true reference resources, universities often have excellent information.

Mudd Math Fun Facts - A collection of over 100 fascinating math tidbits that lead into broader areas
of mathematics.

Merlot - A site with links to an assortment of sites, including mathematical sites. Includes
a reviewing system so you can see if other people liked the sites before you go.