A printable reference: the symmetry operations, the point-group flowchart, the 14 Bravais lattices, Hermann-Mauguin symbols and the 17 wallpaper groups.
Molecular point groups with their operations and character tables, the 230 space groups with a cell builder, and the 17 wallpaper and 7 frieze groups drawn live. The tool needs JavaScript, and WebGL2 for the 3D views; these are the pages it offers: