A dataset was recently made available of all FTP sites in the IPv4 address space that allow anonymous access. Below is a heatmap showing where those sites are located. It was made by using the GeoIPLookup tool to geolocate each IP address, and then bucketing sites by proximity. For this plot, I've combined sites within a range of 0.3 degrees of latitude/longitude. In other words, two sites that are closer than 0.3 degrees to each other, will be bucketed into the same data point. Each data point was then weighted on its number of constituents. Finally, the weights were distributed on a natural log scale, with a minimum value of 1, to provide the weighting and gradient for the heatmap itself.