With Wordle you can easily create a visual word-frequency cloud of any copied text, blog site, or tags from a Delicious site. In a matter of seconds your beautiful graph can provide information that is educational or useless, but regardless of the result it is fun and quite stunning to look at. Below is a Wordle of President Obama's speech on racism.
There are many educational uses of Wordle: ProfHacker published an article on Using Wordle in the classroom, the SlideShare slideshow Forty-Three Interesting Ways to use Wordle in the Classroom includes a wealth of ideas for teaching, and author Soctt Westerfeld's practical blog on eliminating overused words includes a word cloud of his novel Leviathan after the first draft.