Sickweather uses an algorithm to sort through publicly available information on social networks, and cross-references it with geographic data to provide "weather maps" of reported symptoms. Its web site promises to alert users of when the next stomach bug will be passing through town or what neighborhoods are more notorious for chronic illness, based on what users are posting about the sneezes or sniffles they have.
Although the site is still in beta mode, it got me thinking about all the possibilities for pharma - this is the type of thing that could translate really well into a mobile app, or maybe allergy sufferers could use it to check pollen and dust levels in their town on a daily basis. It also has implications for people who travel frequently and want to see what illnesses are popping up in their chosen destination. The site also lets people keep track of their own health and that of their friends and family, meaning it has implications for caregivers too.