Word clouds are visualizations of word frequency.  They allow for graphical analysis of text and have numerous uses in the classroom.  

Wordle: Mashed Library Pancakes and Mash interestsphoto © 2011 Paul Stainthorp | more info (via: Wylio)
Three online tools to generate word clouds are:

Wordle:  Very straightforward and easy to use

TagulEach word in the final product is attached to a Google search of the term

TagxedoThis tool allows for the most customization of the final product; however, you must install Microsoft Silverlight (free) to use it.  When you select “Create” you will be led through the installation process.