Brad Borevitz created this neat little program to analyze the State of the Union addresses given by US Presidents from 1790 to 2006:
SOTU allows you to explore how specific words gain and lose prominence over time, and to link to information on the historical context for their use. SOTU focuses on the relationship between individual addresses as compared to the entire collection of addresses, highlighting what is different about the selected document. You are invited to try and understand from this information the connection between politics and language–between the state we are in, and the language which names it and calls it into being.
For each State of the Union Address, the analyzer also measures the Flesch-Kincaid score, a controversial yet popular readibility index to suggest at which grade level in an American school for which the text is appropriate. The lowest score (grade level 7.1) was George W. Bush's State of the Union address on February 27, 2001.