I haven’t tried this extension to OpenOffice.org, because I don’t use Windows, but it sounds interesting (if not misused or abused as often happens with “readability” scores). Would like to hear from someone who has used it.
The Readability Report tool scores your document for readability, cohesion and information density. These scores provide the author with an indication of how well the intended audience will understand the text. The scores use a variety of computational linguistic techniques to determine the reading level of the text.