A document reader which can summarize important points in a given document

When I look at a very long ebay item description or a blog or a web page, I know what to look for. For example things like its broken, selling for parts for an ebay listing may be mentioned as a matter of fact where it should be the key fact. Or when you are looking a doorway web page, the software should say "this is a door way web page and has no content". What I would like is a good software which automates what a keen individual can find and show in a sidebar. An additional customization capability which would allow us to specify what we want to look for would make it even more useful.