Google N-gram Viewer - tracking social change

A recent article in Science discusses the use of the data encapsulated in Google Books to analyse social trends by looking at the frequency of words or phrases over time. Google has made this data available, and perhaps more usefully, developed a tool (Ngram Viewer) that allows exploration of the data online. So for example, we can see below that the frequency of the phrase "corporate social responsibility" has been trending upwards since the 1960s, while the use of "environmental sustainability" exploded after 1985.

UPDATE: An interesting critical view on the data set used (Google Books) from the humanities at Stanford University's ARCADE