There are some awesome image tools available on the Web of which many are free to use. More sites are using Word Clouds (also called Word Trees and Word Visualization) as sites such as Wordle become more popular. Below is a visualization created of my Home page with size indicating frequency of use. I can imagine that this sort of visualization may be very useful for search engine optimization (SEO) purposes (e.g. when analyzing competitors Websites using a visualization such as that below is a very simple means of determining the words used on a Webpage).
Wordle tip: Many people ask how to keep phrases and expressions intact with Wordle (i.e. how can words be kept together with Wordle?). Well all that needs be done is enter the ~ (tilde) character between words that need to be kept together e.g. enter Registered~Training~Organization to ensure that Wordle shows this term as a phrase rather than separating the words.