This program allows you to search through the google books database for specific words to see how often those words were used in published works throughout time. The results are displayed on a graph. You can search individual words, search phrases, compare words and at the bottom, links are provided to see words in the usage during a specific time period. For example:
Here is a graph on the usage of "fu.ck" from 1800 to 2008:
And here is a comparison of "fu.ck" to "intercourse" for the same time period:
And here is a quote that I found by searching for "fu.ck" between 1697 and 1705:
And wo unto them that are with child, and to them that give fu.ck in those days.
As you can see, it is very academic.