Monitoring Symptom Search Trends

Google has a site that captures information about how people search for flu information. It claims to be able to predict the spread of flu up to two weeks faster than traditional means. I worked on a system with similar aims. It analyzed point-of-sale data from stores for over-the-counter remedy sales. The aim was to predict the spread of certain kinds of symptoms that people might self-medicate for. It has been suggested for detecting some slow-moving bio terror attacks. More on Google's work in the NYT. Lawyers consider the privacy implications.