Over at Rap Genius, they've built a clever little tool called Rap Stats, which indexes a a compendium of rap lyrics and allows just about anyone chart the frequency of just about anything over the last twenty-odd years of rap songs.
But as Rap Genius notes itself, the tool is much more than that and, in many ways, offers up a salient lens from which to view the last few decades in popular culture. The rise of the iPhone and the demise of Blackberry? The sudden boom of the club drug Molly? The ages-old debate surrounding the virtues of money, power, and respect? They're all captured here in exquisite detail.