Google has launched Google Flu Trends in USA to let you find up-to-date influenza-related activity estimates for each of the 50 states. “Our team found that certain aggregated search queries tend to be very common during flu season each year. We compared these aggregated queries against data provided by the U.S. Centers for Disease Control and Prevention (CDC), and we found that there's a very close relationship between the frequency of these search queries and the number of people who are experiencing flu-like symptoms each week. As a result, if we tally each day's flu-related search queries, we can estimate how many people have a flu-like illness.” [Google Blog]