FYI: Google's ngram viewer

[Adam Hodges]

In 500 Billion Words, New Window on Culture
By PATRICIA COHEN
New York Times
December 16, 2010

With little fanfare, Google has made a mammoth database culled from
nearly 5.2 million digitized books available to the public for free
downloads and online searches, opening a new landscape of
possibilities for research and education in the humanities.
http://www.nytimes.com/2010/12/17/books/17words.html?hp

Google's ngram viewer:  http://ngrams.googlelabs.com/