Hyperbolic Links
NonEuclid- Hyperbolic Geometry Article + Applet. This provides an excellent tool for experimenting with the Poincare disk.
Here's a great little applet to help you experiment with Triangle Area in the Poincare disk.
Neutral and Non-Euclidean Geometries. This is basically a geometry textbook on line.
Spherical Links
The Geometry of The Sphere This article is about the basic properties of spherical geometry, such as the nature of lines, points, angles, and polygons. This starts out by talking about the properties of a sphere, then going to great circles, and the notion of distance on a sphere. Next there is mention of area and the area of objects such as a lune (moon shaped figure) and the spherical triangle. (the plane triangle's spherical counterpart) There is then Giraud's Theorem (which explains the total angle measure of a spherical triangle) and its consequences. The paper concludes by proving Euler's theorem of polyhedra, (the sum of the vertices and faces is two more than the number of edges) therefore returning to Euclidean geometry at the end. This is a very informative introduction to the features of spherical geometry.
Invisible Architecture - The NanoWorld of Buckminster Fuller
This series talks about the Engineering genius of Fuller in designing his geodesic domes, and the later discovery of the Buckyball, a new form of carbon which got his name. Fuller wanted to enclose a lot of space while using the least material, so thereupon ecided on making something based on the icosahedron, and made a dome out of this. The carbon molecule scientists discovered, also encloses the most shape with the least material and echoed his dome in shape. Therefore the world of the microscopic echoed the large world of architecture. This article talks about the history of architecture from ancient times to the present, Fuller's history and philosophy, and the method he used to make his dome. (which he based on a sphere) Fuller's inspration from his designs came from nature, and in nature one found a counterpart of his work. This is a good read for those who want to know about the relationships between chemistry and geometry.
Escher Links Here are various random links about Escher.