Tag Crowd  is an interesting site created by Daniel Steinbock, a doctoral student in Design and Education at Stanford University. By using current ideas about tag clouds and word frequency visualization, Steinbock has created a very easy to use Tag Cloud generator that allows an individual to zero in on a particular  website, or text source (of any size..you can copy and paste in a hunk of your dissertation if you like..I did :) and to then, with a simple click create a visual representation of word frequency usage in that text. Other cloud generators examine RSS feeds such as MakeCloud, but Steinbock's site is especially easy to use and useful for encouraging student writers (or any writers really) to reflect in new ways on how they are using language. The most straightforward application I can see for my own students is simply to make them aware of tendencies toward slang and toward unnecessary repetition in essays. To SEE how you've actually used "that" fifty times in the space of 700 words is telling! :)