Have you tried Wordle?
Wordle is a fun application that generates “word clouds” from text that you provide, such as a blog. It contains the 150 most-used words from the text, with more frequently used words appearing larger and more prominent in your cloud. You can make your cloud your own by customizing it with different fonts, layouts and color schemes. Below is the Wordle cloud for our blog.
Wordle does a great job of painting a picture of what your blog is talking about. Check it out and create one for yourself: http://www.wordle.net. It’s fun and useful!