Hello, We have made the Jigsaw visual analytics system available to anyone for download. The link can be found at http://www.cc.gatech.edu/gvu/ii/jigsaw. Jigsaw may be useful for understanding collections of text documents -- It combines computational text mining techniques with interactive visualizations. The system just requires that you have java on your computer. The website above includes a tutorial document as well as a series of short tutorial videos. The site (and distribution) also includes a number of example document collections in a convenient XML-ish format. One that may be of special interest to this community is a collection of all InfoVis and VAST papers -- not the full papers' text, but the title, abstract, authors, conference, year, and other metadata.
This site is generously hosted by Macrofocus GmbH, developer of TreeMap and other fine visualization tools