Superfastmatch: A text comparison tool by Donovan Hide.
Slides on a Chrome extension that compares news stories for unique content.
Would be interesting to compare 24-hour news channels both to themselves and to others on the basis of duplicate content.
Could even have a 15 minute, highlights of the news and deliver most of the non-duplicate content (well, omitting the commercials as well) for any 24-hour period.
Until then, visit this project and see what you think.