This article is from the sci.fractals FAQ, by Michael C. Taylor and Jean-Pierre Louvet with numerous contributions by others.
The Mandelbrot set is the set of all complex "c" such that
iterating "z" -> "z^2" + "c" does not go to infinity (starting with "z"
Other images and resources are:
Frank Rousell's hyperindex of clickable/retrievable Mandelbrot images
Neal Kettler's Interactive Mandelbrot
Panagiotis J. Christias' Mandelbrot Explorer
2D & 3D Mandelbrot fractal explorer (set up by Robert Keller)
Mandelbrot viewer written in Java (by Simon Arthur)
Mandelbrot Questions & Answers (without any scary details) by Paul
Quick Guide to the Mandelbrot Set (includes a tourist map) by Paul
The Mandelbrot Set by Eric Carr
Java program to view the Mandelbrot Set by Ken Shirriff
Mu-Ency The Encyclopedia of the Mandelbrot Set by Robert Munafo