From Miguel Helft:

In early February, for example, the C.D.C. reported that the flu cases had recently spiked in the mid-Atlantic states. But Google says its search data show a spike in queries about flu symptoms two weeks before that report was released. Its new service at google.org/flutrends analyzes those searches as they come in, creating graphs and maps of the country that, ideally, will show where the flu is spreading.