handsonmath.com http://www.handsonmath.com/
Geometric model building courses to improve understanding of geometry, using a Matrix kit for sale on the site that can be used in order to create the models yourself.
Platonic Spheres http://www.neubert.net/PLASpher.html
The five regular polyhedra mapped onto the surface of their surrounding spheres, which can be rotated in java applets. Also includes a discussion of the mathematical properties of the shapes.
Polyhedra Collection by V. Bulatov http://www.physics.orst.edu/~bulatov/polyhedra/
An extensive library of images and vrml models of the shapes. Includes uniform polyhedra, stellations, spherical platonic polyhedra, polyhedral mirrors, hyperbolic tesselations, plates from Bruckner's 1906 polyhedra book, and a stellation java applet.