A co-worker introduced me to wordle, which has become one of my favorite toys. It makes a word cloud that visualizes the word frequency in a passage you copy to the wordle site. You can experiment with different layouts, colors, and fonts until you find the image that makes you most content. This seems like a good tool to use in writing; it could allow you to see what the dominant words (and the ideas linked to them) are in a chapter or scene.