This report at Drudge strikes me as pretty creepy:

  GOOGLE will launch a new tool that will help U.S. federal officials "track sickness".
  "Flu Trends" uses search terms that people put into the web giant to figure out where influenza is heating up, and notify the Centers for Disease Control and Prevention in real time.
  GOOGLE claims it would keep individual user data confidential: "GOOGLE FLU TRENDS can never be used to identify individual users because we rely on anonymized, aggregated counts of how often certain search queries occur each week."

  It's legal for Google to do this: From a legal standpoint, when you send a query to google, that query belongs to them and they can voluntarily disclose it. But do we want Google establishing such a cozy relationship with the federal government? I don't. I've thought about writing an article calling for a Search Engine Privacy Act, to prevent unauthorized use and disclosure of search queries. Stories like this make me think I may put that on the front burner rather than the back burner.