(original link, no longer active – http://whoissick.org/sickness/) Who is Sick? is a Google map-based application where you can enter data detailing the symptoms of your illness, add it to a map of your location, and see who in your particular area is also sick. Kinda interesting, especially in my neighborhood.
The site didn’t survive. I wish I could go back and look at what info they gathered. In the third year of the Corona Virus pandemic, this would have such interesting ramifications.