Today I was having fika and talking with Jayadev S. Athreya. He showed me some very cool Voronoi diagrams. These are described as follows:

Fix an integer g. Then take a region on the plane and list all the integer points whose gcd are exactly g. Finally, draw the Voronoi diagram of those points.

I liked it so much that, after some experimentation, and with some help from my friend Codex, I got the following applet.