Patterns of Reflection at http://patternsofreflection.com examines geometric art that uses kaleidoscope-like reflective techniques. I think it's beautiful; sometimes other people do, too. It includes a page of 155 repeating patterns for free use that may be of interest to designers, 3D modelers, scrapbookers, artists and geometry teachers at http://patternsofreflection.com/index.php/free-tiling-patterns/