I thought I’d just mention Patrik Wallström’s interesting project named Creeper. He basically offers a URL for an image to display on the site you run/admin, and then his server checks which IP addresses that gets the image and then cross-checks those addresses against a list of IP ranges of known swedish organizations, government agencies, political party headquarters and more.

An ingenious way to get some degree of knowledge about who looks at what and when. At least if a large enough amount of people display the Creeper icon: