NPR reports on Google's new searchable database made up of of 500 billion words. Google's project has been controversial because it involved scanning 5 million books, many still covered by copyright. Google got around that by using the text from these works as a collection of words and phrases removed from their context other than date.
Scholars are using it to show trends in language. And I can think of many authors who will love being able to research the evolution of slang and idioms.
You can go play for yourself here.
You can look at it from a more cultural perspective here.