Google recently put out a new tool that is both fun to play with and potentially an interesting research tool. It's called Google Correlate, and it essentially lets you see both the spatial distribution of what people are searching for as well as find search terms that are correlated over time.

One example they give is comparing a time series of flu activity with searches for terms like "sore throat" and "fever" to see whether or not they match. You can upload your own time series data or just look for correlations by typing in search terms. Check out the tool or the comic book overview of it.