W4T Undergraduate Geometry Web Sites for Teaching Undergraduate Geometry Convex Hull Algorithms , by Greg Parent at Middlebury College. This is a Java applet for the Graham Scan and Jarvis March algorithms.
Additional applets are at their Projects page.
Euclid's Elements , annotated by David E.Joyce at Clark University. This is an excellent web tour through one of the greatest works of all time. Geometry , by Paul Bourke at Swinburne University of Technology, Australia Mostly this is a well kept gallery, with a special page on the Platonic solids. It also gives some fundamental algorithms, such as finding distances and intersections. You can go up one level to see other pages, notably his Projections, which includes conformal maps in the complex plane.