Number Theory:

Modular Arithmetic Calculator
Modular Arithmetic Calculator
Dario Alpern's number theory site
MathPages: Number Theory.
Tool and the Fibonacci numbers

Knots:
The KnotPlot Site

Algebraic surfaces and singularities:
Herwig Hauser's singularities
Algebraic Surface Gallery
Imaginary
AlgebraicSurface.net
Algebraic surface
4d animation

Fractals:
Wikipedia: Fractals
Fractal Zoom Mandelbrot Corner
Fractals unleashed

Web pages of the American Mathematical Society:
Mathematical Moments
Mathematical Imagery
AMS Math Samplings

Mathematical humour:
Collection of by Andrej and Elena Cherkaev
UNipissing site
The komplex plane
Erich Friedman web site
The Math Humor Page
Foolproof: A Sampling of Mathematical Folk Humor
Wikipedia on Math Humour
Ivan Fesenko's collection of Murphy's Laws
More links at allmath.com
More links at EqWorld
More links at about.com

For math teachers:
JUMP Math
Math Forum
Links for high school students and teachers

Other stuff:
Math in daily life
Museum of Mathematics
ihatecalculus.com
The Power of Exponential Growth

Last update: December 6, 2010