I was recently reminded of Brad Borevitz's excellent State of the Union text analysis project. This year, he's added a tool that lets us graph the frequency of words against each other. Here's an interesting example, over time the use of the word "freedom" has risen dramatically, while "liberty" has remained fairly steady.
Maybe this is an indication that politicians prefer to use language that's more open to different interpretations. Maybe it's just linguistic fashion. Now I want a similar tool that visualizes word use in major newspapers.