Cut the Knot
These Interactive Mathematic Miscellany and Puzzles and related web sites are offered to further mathematics education and for personal enjoyment. Shows how to solve classic and challenging mathematical problems.

Electronic Journal of Undergraduate Mathematics
The Furman University Electronic Journal of Undergraduate Mathematics is a forum for the publication of  mathematics research papers written by undergraduate students. 

EqWorld
The main purpose of creating the EqWorld web site is to help the widest possible audience of researchers, university teachers, engineers and students to sail more easily through the ocean mathematical equations (differential, integral, functional, etc.) and their solutions.

Famous Problems in the History of Mathematics
The purpose of this site is to present a small portion of the history of mathematics through an investigation of some of the great problems that have inspired mathematicians throughout the ages.

Free Online Textbooks, Lecture Notes, Tutorials, and Videos on Mathematics

How to Write Proofs
Proofs are the heart of mathematics. If you are a math major, then you must come to terms with proofs--you must be able to read, understand and write them. What is the secret? What magic do you need to know? The short answer is: there is no secret, no mystery, no magic. All that is needed is some common sense and a basic understanding of a few trusted and easy to understand techniques.

The MacTutor History of Mathematics archive
This extensive archive contains biographies sorted by alpha order or chronologically, history topics, famous curves index and the mathematician of the day. From the University of St. Andrews, Scotland.

Mathematical Atlas
The Mathematical Atlas is a collection of short articles designed to provide an introduction to the areas of modern mathematics and pointers to further information, as well as answers to some common (or not!) questions. The material is arranged in a hierarchy of disciplines, each with its own index page

Mathematical Spectrum
Mathematical Spectrum is a magazine for students and teachers of mathematics in universities, colleges and schools worldwide. It may be read by anybody interested in mathematics as a recreation. Mathematical Spectrum publishes articles from all branches of mathematics, as well as regular features on mathematics in the classroom, a computer column, letters, problems and solutions, book and software reviews. We welcome original student contributions and award annual prizes for the best ones published.

MASS
Mathematics Advanced Study Semesters (MASS) is a new semester-long program at Penn State which provides a comprehensive mathematical environment for a group of talented undergraduate students selected from U.S. colleges and universities and brought to the University Park campus. The program combines advanced learning with research initiation. It may be characterized as a "domestic study abroad" program (Fall semesters only.)

Math.com
The world of math online. Topics range from homework help to practice, ask an expert, calculators and tools, and most math disciplines including the most advanced.

Math Archives
In these pages, you will find links to various WWW resources on Mathematics. They are organized by topics. In addition, we have added two features to make this a useful database for you: use of additional keywords to describe a site and use of icons to quickly show the level of mathematical background to read the materials on the site and the type of materials available.

Math Forum
The Math Forum is a leading center for mathematics and mathematics education on the Internet. The Math Forum's mission is to provide resources, materials, activities, person-to-person interactions, and educational products and services that enrich and support teaching and learning in an increasingly technological world.

MathNerds
MathNerds provides free, discovery-based, mathematical guidance via an international, volunteer network of mathematicians. MathNerds does not supply answers to homework, take home tests and the like; rather, they provide hints, suggestions, and references to help their clients understand and solve their mathematical problems.

Math Pages
Several hundred articles on all areas of Mathematics are archived here. Subjects include: Number Theory, Combinatorics, Geometry, Algebra, Calculus & Differential Equations, Probability & Statistics, Set Theory & Foundations, Reflections on Relativity, History, Physics, Music, Animated Illustrations and Quotations.

MathServ
Each web-page in the MathServ system is an interface between the user (you) and a computational engine (the Mathematica kernel). Mathematica is a very powerful computer algebra system that is capable of performing many different types of mathematical calculations, both numerically and symbolicaly. It is not necessary for you to know anything about Mathematica, the HTML language, or any other computer language to use this toolkit. From Vanderbilt University.

MathWorld
MathWorld is a comprehensive and interactive mathematics encyclopedia intended for students, educators, math enthusiasts, and researchers. Like the vibrant and constantly evolving discipline of mathematics, this site is continuously updated to include new material and incorporate new discoveries.

The Most Common Errors in Undergraduate Mathematics
The Most Common Errors in Undergraduate Mathematics - A list distributed to students by a professor at Vanderbilt University who was tired of seeing these same old errors over and over again.

Mudd Math Fun Facts
Mudd Math Fun Facts Fun Mathematics Problems from Harvey Mudd College.

Online Calculators
Here are the 20 most popular Online calculators courtesy of Cochise Community College.

Practical Foundations of Mathematics
Practical Foundations collects the methods of construction of the objects of twentieth century mathematics:

1. First Order Reasoning
2. Types and Induction
3. Posets and Lattices
4. Cartesian Closed Categories
5. Limits and Colimits
6. Structural Recursion
7. Adjunctions
8. Algebra with Dependent Types
9. The Quantifiers

Rose-Hulman Institute of Technology Undergraduate Mathematics Journal 
Rose-Hulman Institute of Technology Undergraduate Mathematics Journal is devoted entirely to papers written by undergraduates on topics related to mathematics.

S.O.S. MATHematics
Browse more than 2,500 Math pages filled with short and easy-to-understand explanations - from simplifying fractions to the cubic formula, from the quadratic equation to Fourier series, from the sine function to systems of differential equations - this is the one stop site for your math needs.