Google's old idiom was that if they knew what the world was searching for, they could find out what was most important at the time.
Facebook took it one step further with Lexicon; if you can aggregate all of the words in everyone's status updates, you can measure the mood of the collective.
The graph has two options, positivity and negativity, and you can filter on them over time. The Gross National Happiness is the difference between the two.
Examples of positive or happy words include "happy," "yay" and "awesome," while negative, or unhappy words, include "sad," "doubt" and "tragic." We also did a brief survey of some Facebook users, which showed that people who use more positive words, relative to the number of negative words, reported higher satisfaction with their lives.
Most people are happy during the holidays and summertime, but it's fun to look along the graph for spikes and dips.
If you are really interested in this type of social data, Facebook has a "data hub" where you can dig into all these things.