Check out this cool little tool: Google N-Grams
It shows a graphical representation of the frequency words used in books over a rangeof years. It is based on on all the books google has scanned into their database to date.
This TED talk is what turned me on to the project.
The project, the tool and the lecture are all quite entertaining.
Here are some graphs I created playing with the tool. Graphic data, especially that which is based on sentiment represented by our societies authors, gives us amazing clues into how perception and reality intersect.