I had heard about Google’s Ngram viewer a while ago, but it was only recently I saw some research that had used it—about the expression of emotions in twentieth-century books. If you go to the Ngram site, it opens up with a sample already in place to help exploration.
There are some limitations (including that the data only relates to published books), but for writers, historians, anyone interested in culture, the Ngram viewer can help to create new insights. It is really worth taking a while to get to know it.
Stephen J. Williams 