A very extensive site is The Geometry Junkyard.

A related site, giving many applications of geometry in various fields, is Geometry in Action.

An undergraduate site from the University of Kentucky can be found here.

Here us a hypercube site by Rudolf Rucker.

Here is a site that let's you design your own hypercube, and higher-dimensional versions.

Thomas Banchoff
Last modified: Sun Mar 19 13:19:43 EST 2000