http://matemilano.mat.unimi.it   http://www.atractor.pt/simetria   On the website of the Portuguese association Atractor (see below) you can find the pages dedicated to their (slightly enlarged) copy of the exhibition "Symmetry, playing with mirrors", constructed in collaboration with the staff from Milan.In particular, we point out:   http://www.atractor.pt/simetria/17padroes   where you can see interesting animations about the 17 wallpaper groups;   http://www.atractor.pt/simetria/matematica   a partly interactive version of some leaflets of the exhibition. http://www.divideo.it/personal/todesco/java/polyhedra   website by Gian Marco Todesco; it contains nice animations of the regular polyhedra. http://www.quadernoaquadretti.it/