**Number Theory:**

Modular Arithmetic
Calculator

Dario Alpern's
number theory site

MathPages: Number
Theory.

**Knots:**

The KnotPlot Site

**Algebraic surfaces and singularities:**

Herwig
Hauser's singularities

Imaginary

AlgebraicSurface.net

Algebraic surface

4d
animation

**Fractals:**

Wikipedia: Fractals

Fractal Zoom
Mandelbrot Corner

**Mathematical humour:**

Collection of
by Andrej and Elena Cherkaev

The komplex
plane

The Math Humor
Page

Foolproof: A
Sampling of Mathematical Folk Humor

Wikipedia
on Math Humour

More links at
allmath.com

More links at
EqWorld

More
links at about.com

**For math teachers:**

JUMP Math

**Other stuff:**

Museum of Mathematics

The Power of Exponential
Growth