The Kepler Conjecture - A great source of information on the recent proof of Kepler conjecture about sphere packings.

Problem of the Minimum Rotation Surface - Java applet demonstrating the catenary.

The Geometry Forum - An electronic community focused on geometry and math education based at Swarthmore college.

Geometry in Action - This page collects various areas in which ideas from discrete and computational geometry meet some real world applications.

The Geometry Junkyard - Usenet clippings, web pointers, lecture notes, research excerpts, papers, abstracts, programs, problems, and other stuff related to discrete and computational geometry.

Erich's Packing Center - Graphics and links for various packing, tiling and covering problems.

Erich's Combinatorial Geometry Page - Various topics collected by Erich Friedman, Stetson University.

Fibonacci Numbers and the Golden Section - This is the Home page for the Fibonacci numbers, the Golden section and the Golden string. Department of Computing School of Electronic Engineering, IT and Mathematics, University of Surrey, UK.

Wilson Stothers' Cabri and Conics Pages - A site devoted to (mainly projective geometry) illustrated by Cabri II and CabriJava.

Tim Lister's Hyperbolic Geometry - Cabri constructions for the demonstration of the basic concepts of hyperbolic geometry in the Poincare disc model.

Manipula Math with Java - Java applets demonstrating many geometrical and other theorems

Steiner Trees - Open Problems with Steiner Trees.

Bette Veteto's Homepage - History of Mathematics, very strong on geometry.

Steiner Surfaces - Mathematical descriptions and ray-traced images of every type of Steiner surface

Open Problems - Collected by Jeff Erickson. Mainly in geometry.

Mathematical Surfaces - A collection of parametric and implicit equations.

Open Problems in Discrete and Computational Geometry - Compiled by Jorge Urrutia.

e-zgeometry - An interactive geometry site for high school teachers and students with an interactive textbook, class video clips, geometry projects, geometry glossary, and resources.

The Educational Validity of Visual Geometry - Ph.D. thesis of Marius Blok (Hull, U.K., 1998). 'Educational Geometry' is based on visual geometry, linked to philosophy and visual art and the learning is free of the application of formulae or the use of computations.

Bob's Pages - A collection of interactive geometry applets. Topics include polyhedra, Poncelet's porism,Mandelbrot set, Steiner porism,Pappus's chain,Repulsion polyhedra and stereo pictures

Wilson Stothers' Inversive Geometry and CabriJava Pages - A page on inversive geometry with CabriJava illustrations. Includes Steiner's Porism and the arbelos.

Dearing Aviation - Describes solutions of Apollonius' Problem in two and three dimensions.

Colin and Greg's Golden Ratio Page - This is an informative site on an interesting aspect of Geometry: The Golden Ratio.

Geometry in a Triangle - A lot of classic constructions in the triangle. And more non-classic. Free. Applet and programs for Windows, Mac OS9 and Mac OSX.

Allexperts Geometry Q&A - Volunteer tutors help you work through your geometry problems for free.

ArXiv Front: MG Metric Geometry - Metric geometry section of the mathematics e-print arXiv.

On the Fourth Dimension - Concepts of the fourth dimension explained simply

The Geometry of the Sphere - This material was the text for part of the Advanced Mathematics course in the High School Teachers Program at the IAS/Park City Mathematics Institute at the Institute for Advanced Study during July of 1996.

The Math Forum's K-12 Geometry - Select classroom materials for geometry teachers and students, software for geometry, interactive geometry classroom resources, Internet projects, selected geometry elsewhere on the Internet, and public forums for discussing geometry.

Math Forum: Geometry POW/POM Search - Search the Geometry Problem of the Week's archive of creative, non-routine challenges, as well as submissions and commentary, dating back to 1993.

Xah: Visual Dictionary of Special Plane Curves - A Visual Dictionary of Special Plane Curves with graphics.

GLaD: Introduction - A historical introduction to a new Euclidean construction by David Goldenheim and Daniel Litchfield. Dynamic Geometer's Sketchpad files are included.

Intensified Geometry Curriculum Review - A comprehensive, illustrated review of concepts covered in an Intensified Geometry textbook/class.

A Gallery of Interactive On-Line Geometry - At the Geometry Center.

GeomNet - Family of geometric computing servers execute a variety of geometric algorithms on behalf of remote clients, which can be either users interacting through a Web browser interface or application programs connecting directly through sockets.

Diamond Theory - Plato tells how Socrates helped Meno's slave boy "remember" the geometry of a diamond. Twenty-four centuries later, this geometry has a new theorem.

ArXiv Front: SG Symplectic Geometry - Symplectic geometry section of the mathematics e-print arXiv.

Encyclopedia of Triangle Centers - By Clark Kimberling. Over 1000 triangle centres in a searchable compilation with diagrams.

Geometry and the Imagination in Minneapolis - Geometry exercises for a two-week summer workshop led by John Conway, Peter Doyle, Jane Gilman and Bill Thurston at the Geometry Center in Minneapolis, June 1991.

Packomania - This site collects the best known packings of equal objects in containers together with source codes to obtain them numerically.

Math 3210 - Higher Geometry I - Course notes by Bill Cherowitzo.

Cuboid and Cube Surface Distances - A java applet with substantial analysis related to distances on a rectangular box.

Wallpaper Groups - Images and descriptions of the 17 plane symmetry groups.

Geometry Page from Interactive Mathematics Miscellany - More than 120 articles on topics in elementary and not so elementary geometry, many with interactive Java illustrations and multiple proofs.

Geometry Homework Help - GeometryHomework.com offers homework help and online tutorials for grades 7-12 with detailed lessons, quizzes, interactive tests and solved problems.

Projective Geometry - Rudolf Steiner's approach.

Geometric Group Theory - Information and resources about geometric group theory and low-dimensional topology. People, groups, meetings, links.

Open Problems from the Geometry Junkyard - Complied by David Eppstein (University of California at Irvine).

The Fundamental Theorem of Projective Geometry - Maska Law.

Geometry Formulas and Facts - Excerpts from the 30th Edition of the CRC Standard Mathematical Tables and Formulas (1995), namely, the geometry section minus differential geometry.

Important Concepts from Projective Geometry - Webtext by Paul Beardsley.

Lecture Notes on Projective Geometry - By Balázs Csikós. Budapest Semesters in Mathematics. In DVI format.

Projective Geometry for Multiple View Analysis - A new framework for studying the problems of camera calibration, motion determination, and 3D structure reconstruction in the most general case of totally uncalibrated views.

Menelaus' Theorem and its Applications - Theorems involving Menelaus' theorem and some applications of Menelaus' theorem to geometry problems.

An Introduction to Projective Geometry (for Computer Vision) - The purpose of this monograph will be to provide a readable introduction to the field of projective geometry and a handy reference for some of the more important equations. HTML, PS or PDF versions.

The 4th Dimension - Visual and mathematical descriptions of higher dimensional objects, with Java applets for displaying and rotating images such as Steiner surfaces, Klein bottles, and minimal surfaces.

Morley's Miracle - A discussion of Morley's famous theorem and the research of which it was a tiny part. 5 proofs are given including J. Conway's, D. Newman's, and A. Connes'.

Math Forum: Search geometry-research - Geometry professors and instructors may keep informed of the latest research conducted in their field at the geometry-research discussion list.

Math Forum: Search geometry-forum - Those interested in examining the previous incarnation of the Math Forum may search the archives of the Geometry Forum.

Geometry Activities - By Ephraim Fithian.

Center of points in 2 or higher dimensional space - It provides important formulations for finding a center of points in 2 or higher dimensional space. It can be used in drawing delauney triagulation and voronoi diagram in two or higher dimensions. It also describes how many points are required in defining a center in n-dimensional space.