Leximancer is a text mapping and mining application that creates visualizations of texts that can be made available over the web in interactive form. See the Leximancer Gallery.
Here is what the web site says about the techniques used:
The technology behind Leximancer is based on Bayesian theory. Simply put, this idea says that the bits and pieces of evidence which you see can predict what is actually happening. We have applied this to text, so that the words which make up a sentence predict the concepts being discussed. (Leximancer Techniques)
For some reason I don’t get, the site has mystical graphics including what looks like crystal ball for the main graphic presence. This combined with the name makes it sound like the tool will work by magic.