I recently asked a group of Googlers which day of the week had the most Google searches for the word ‘hangover.’ Most of them chose Sunday or Monday, although one party animal opted for Tuesday.

We can find the definitive answer – Sunday – by using a nifty tool called Google Insights for Search. This tool can be used to examine individual queries, but it can also compare search volumes for different queries. For example, searches for ‘vodka’ peak every Saturday, one day before the ‘hangover’ peak. The exception to this regular weekly pattern occurs once a year, on New Year’s Eve.

Searchblog’s John Battelle has called Google ‘the database of intentions,’ because search queries provide insights into people’s interests, intentions, and future actions. Needless to say, such insights can be very useful to businesses. Free tools like Google Correlate and Google Insights for Search enable you to use that database of intentions to ‘predict the present’ and better understand your customers’ behavior in real time.