“Wordle is a toy” for creating “word clouds” like the one shown above. You can paste text, or point Wordle to a URL and it will create a word cloud with the more important words shown as larger. *The above cloud was generated from the feed for the Cape Fear River Steamers site.
I’m not sure what algorithm they use to assign the “importance” of the words in a work, but I like this. You get a quick, visual, image of the words which make up the gist of an article.