There was a fantastic article in the NYT about how Google tracks the emergence and spread of the flu virus throughout the country.  Since users search for Flu symtoms at the onset of the bug, Google can detect the virus' spread based on aggregate search data.  This information is a huge advantage in containing the virus' spread and in a proactive way, rather than the CDC's data which is collected retr-actively from health care professionals and clinics, after the fact. 

This is just the tip of the ice-berg in terms of the usage of aggregate data.  We have seen the power in the very basic stats that Facebook provides for our application iGo iWrite.  The demographic data is a valuable tool for targetted advertising.

Read the whole article here.