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.
Google labs has recently launched a new tool called google correlate which helps you find the search patterns which correspond with real-world trends. It lets you compare the time series for instance many search terms vary in popularity over time. To find terms that vary in a similar way to your own time series, enter your data using the link above. At google correlate you can enter a query into the search box above to find search terms that have a similar pattern of activity.
For those wondering about the data Google Correlate contains web search activity data from January 2003 to present. This data is updated weekly.Google Correlate lets you search in two different ways. The US states option lets you find queries which have similar state-by-state patterns. The time series option lets you find queries that have similar patterns across time, you can read the full tutorial here on how to use google correlate.
Google Correlate uses web search activity data to find queries with a similar pattern to a target data series. The results can be viewed on the Google Correlate website or downloaded as a CSV file for further analysis.
Try Google Correlate here at this link.