Using an online tool called "Wordle", I copied and pasted the transcript of President Obama's 2nd State of the Union Address and the website automatically generated a "word cloud" of the text. The more frequently a word is utilized, the larger it appears in the "cloud" (colors are irrelevant). Keep in mind, though, that the user has the ability to specify the maximum amount of words to be rendered. For this speech, I chose 50 as the maximum in this construction. Click on the Wordle for a larger image.
P.S. For a completely different look at the words used by Presidents, check out this version featured on the New York Times website: