Stephen Wolfram analyzed the Facebook world, based on anonymized data from the Wolfram|Alpha Data Donor program. He visits topics from how people friend, how the Facebook world compares to the real one, and how people change with age.
People talk less about video games as they get older, and more about politics and the weather. Men typically talk more about sports and technology than women—and, somewhat surprisingly to me, they also talk more about movies, television and music. Women talk more about pets+animals, family+friends, relationships—and, at least after they reach child-bearing years, health. The peak time for anyone to talk about school+university is (not surprisingly) around age 20. People get less interested in talking about "special occasions" (mostly birthdays) through their teens, but gradually gain interest later. And people get progressively more interested in talking about career+money in their 20s. And so on. And so on.
Worth the full read.