Google Correlate is an experimental new tool on Google Labs which enables you to find queries with a similar pattern to a target data series. The target can either be a real-world trend that you provide (e.g., a data set of event counts over time) or a query that you enter.
A while back, Google showed how Influenza outbreaks correlated to searches for flu-related terms with Google Flu Trends. It helped researchers and policy-makers estimate flu activity much sooner than with previous methods. Google Correlate is the evolution of Flu Trends in that now you can correlate search trends with not just flu cases, but with your own data or other search queries.
After logging in, you can upload any data and leverage Google's huge search history and algorithms to see if there's a correlation over time. Brand managers keen to see if their promotional TV ad campaigns result in echoed online activity searching for their brands (and possibly compared to their competition) can do so with a few clicks. Publishing houses can see whether readers are searching for their magazine, or their online entity. Economists and sociologists pondering if searches for "credit card" and "no interest credit card" decline proportionally to a recovering economy now have a powerful data ally (spoiler: yes, that correlation is true).