All Countries: A list at Mathematics Archives. Sorted strictly alphabetically

American Mathematical Society: Founded to promote mathematical research and education through conferences, contests surveys, publications, employment services, scholarship programs, locating research funding, resources, and outreach. Includes program news and membership information

American Mathematical Society: The AMS on-line bookstore; 3000+ titles and other merchandise

Computational Geometry Pages: Jeff Erickson's directory of computational geometry resources, including bibliographies, journals, software, and related hubs

Elements of Abstract and Linear Algebra, by Edwin H. Connell: Full online book on abstract algebra with emphasis on linear algebra. Format: DVI, PDF, PS and gzipped-PS

Famous Curves Index: Curves you've heard of and curves you haven't, from Astroid to the Witch of Agnesi

Fractal Geometry: An educational resource on the mathematical framework and formalism from the Yale University, covering the concept of self similarity. Includes topical examples, images, algorithms and software

Front for the Mathematics ArXiv: User-friendly front end for the mathematics section of the arXiv (free)

Gerard's Universal Polyomino Solver: Computes from 1 to 3.38 billion solutions with graphic display to each of the 60+ problems of different sizes and shapes. Pieces vary from pentominoes to heptominoes, sometimes in combination. Table summarizes properties and example solution of each problem. [Java required]

graphdrawing.org: Information source for researchers, practitioners, developers, and users working on all aspects of graph visualization and representation

Illuminations: Designed to "illuminate" the new NCTM Principles and Standards for School Mathematics

International Mathematical Union (IMU): Promotes international co-operation in Mathematics. Information about the Union and its executive committee, news bulletins and details of member countries

Journals in Combinatorics: Listed in the Combinatorics Net

Knot a Braid of Links: A selection of links to educational math pages on a wide range of topics. Includes links to learning videos, calculating tools, graphics, and regular text information

MacTutor History of Mathematics Archive: Topics are presented by topic areas, date, or mathematicians. Includes timeline and website search engine

Mandelbrot, Benoit B.: Founder of fractal geometry. Includes biography, vita, publications, interviews, and reviews

Martindale's Calculators: A collection of calculators for the sciences, business and everyday measurements. Organized by subject area

MathSciNet: Math Reviews: AMS database of more than a million reviews and abstracts of math publications (requires subscription)

Netlib: Searchable repository of free numerical software

Number Theory Web: Things of interest to number theorists collected by Keith Matthews

Probability Tutorials: Tutorials in measure theory, lebesgue integration and probability, by Noel Vaillan

S.O.S. Math - Mathematical Tables and Formulas: Large integral tables along with other math tables. Polynomial, trigonometric, logarithmic, hyperbolic. and Laplace transform tables

Statistical Science Web: Hierarchical directory of resources of interest to statisticians with special attention to Australia

Stephen Wolfram: Official website. Includes extensive biographical material, interviews, lists and sample contents of the author's books and other publications, information about Mathematica, and Wolfram's answers to various questions

The Math Page: Arithmetic, algebra, geometry, trigonometry and calculus lessons. From Lawrence Spector from the Borough of Manhattan Community College, The City University of New York

The Straight Dope: On "Let's Make a Deal": Thorough discussion of the problem, with solutions explained

University of St. Andrews: Biography Index: Names are listed alphabetically or by date, from 1680 BC to the present

Virtual Reality Polyhedra: Encyclopedia with virtual reality (VRML) models, history and art of the shapes. Includes background information on each shape, a glossary, guide to names, classroom activities, sculptures by the author, and a bibliography