The software I use to make my images.
Kleinian groupsIndra's Pearls
The website maintained by Prof. David Wright of Oklahoma State University, one of the authors of "Indra's Pearls, The vision of Felix Klein."
Space-filling packingsProf. Hans Herrmann's page
Where I got inspiration for sphere packings and "strip geometry".Bowl of integers
Website (in French) by Nicolas Hannachi on sphere packings with spheres of integer curvature.
Mathematical artMathematical imagery at the American Mathematical Society.
Mathematicians and artists continue to create stunning works in all media and to explore the visualization of mathematics--origami, computer-generated landscapes, tesselations, fractals, anamorphic art, and more.
Optical illusionsAn optical illusion
Optical illusions blog by Brad Honeycutt.
OtherThe History of Measurements
A short history of measurements, by Tiffany Chambers.