University of Massachusetts
Fractal Project: Exploring Fractals
A good beginner's site for fractals - the language is straightforward and requires only minimal experience to be able to understand the topic. (Note: When clicking on links on archived site, they may pause and appear not to be found...
Boston University
Fractal Geometry of the Mandelbrot Set Ii
This web site addresses counting and adding in fractal operations, as well as the role of the Fibonacci sequence in fractal geometry.
Jim Loy
Jimloy.com: Saccheri
This site explains the Saccheri quadrilateral and the importance of his work in geometry.
Other
Georgia Tech: The Four Color Theorem
An explanation and proof of the Four Color Map Theorem. Includes illustrative images and a plethora of information.
University of St. Andrews (UK)
University of St. Andrews: St. Andrews: History of the Four Color Theorem
The University of St. Andrews offers a brief history of the first math problem to be solved with computers.
Boston University
Boston University: Chaos, Fractals and Arcadia
This is an interesting site for information on chaos and fractals. Includes links to interactive activities to learn more.
Boston University
Bu: Fractal Geometry of the Mandelbrot Set
This site progresses in iterations through Mandelbrot and Julia sets to explain fractals and the mathematics behind them.
Wolfram Research
Wolfram Mathworld: Elliptic Geometry
MathWorld offers a brief definition of elliptic geometry and including a brief discussion of its relationship to Euclidean geometry, with links to other related definitions.
Shodor Education Foundation
Shodor Interactivate: Lesson: Fractals
This site provides some links to activities and lesson plans dealing with fractals and chaos.
Other
Mathematical the Four Color Theorem and Computer Proof
This site describes the role of computer involvement in the four color map theorem.
Other
Eal: Fract Ed
A great resource for beginners. The site begins with a definition of iteration of functions, and proceeds from there to discuss fractal dimension.
University of Canterbury
Canterbury: The Konigsberg Bridge Problem
An introduction to the Konigsberg Bridge problem and its relationship to network theory.
University of Illinois
University of Illinois Urbana Champaign: Torus Math: Spherical Geometry Demo
A java applet on this site illustrates the principles or spherical geometry.
Math Words
Math words.com: Elliptic Geometry
The basic definition for what elliptic geometry is is found here.