Wordle: Declaration of Independence
Click image to see larger size.

Above is a Wordle.  It is a visual representation of whatever text you choose to enter into it's engine.  The cool thing is, as you can see from the image, the more a word shows up in the text, the larger it appears in the image. As an example I've chosen the Declaration of Independence.  Now, I know what you're saying: "the most common words in the English language are all that's going to show up".  Not so!!  In the options section of the program you can choose to block certain words.     

In a classroom setting a teacher could use this to introduce the concept of theme; the largest word is what the story is about.  You could have students wordle their own thoughts to see if main ideas emerge.  While technically not a graphic organizer, students who are visual learners will still find this helpful when discussing such abstract themes as main idea, theme and even character interaction and intention.