Sites

Spherical Trigonometry, Arc Distance Formula (Popularity: )
http://www.jqjacobs.net/astro/arc_form.html
Finding the shortest distance between two points on the earth given latitude and longitude. Download ARC_CALC_3, Microsoft Excel version, A Spherical Triangle Calculator by James Q. Jacobs.

NonEuclid - Hyperbolic Geometry Article + Software Applet (Popularity: )
http://math.rice.edu/~joel/NonEuclid/
NonEuclid is a software simulation offering straightedge and compass constructions in hyperbolic geometry.

Non-Euclidean Geometry with LOGO (Popularity: )
http://www.bham.ac.uk/ctimath/reviews/logo.html
Review of a new version of LOGO developed at Cardiff.

The Ontology and Cosmology of Non-Euclidean Geometry (Popularity: )
http://www.friesian.com/curved-1.htm
A philosophical essay.

Seminar on the History of Hyperbolic Geometry (Popularity: )
http://www.math.columbia.edu/~pinkham/teaching/seminars/NonEuclidean.html
Seminar notes by Greg Schreiber.

Non-Euclidean Geometry - Mathematics and the Liberal Arts (Popularity: )
http://math.truman.edu/~thammond/history/NonEuclideanGeometry.html
A resource for student research projects and for teachers interested in using the history of mathematics in their courses.

Non-Euclidean Geometry (Popularity: )
http://www-groups.dcs.st-andrews.ac.uk/~history/HistTopics/Non-Euclidean_geometry.html
A historical account with links to biographies of some of the people involved.

References for Non-Euclidean Geometry (Popularity: )
http://www-history.mcs.st-andrews.ac.uk/history/HistTopics/References/Non-Euclidean_geometry.html
A bibliographic reference list of books and articles on non-Euclidean geometries, part of the MacTutor History of Mathematics archive.