Wordle is a website that can take any text you enter (like this selection from Caesar) and make a word cloud out of it. More common words are larger, and you can customize the shape and colors of the display.
Besides being pretty, it’s also interesting to run text through it and see what is the most common word in a passage. These can spark discussion of the frequency of usage of words in particular cases as well as bringing out themes from the work.
The website requires Java to run, so you may need to install the applet.