I have never NEEDED anything more. Im not sure if this is even downloadable, but its worth a try. Only the most 1337 will try to find this. This isn't some simple product... so here we go.
DESCRIPTION: This site offers anti-plagiarism software (maybe a service) which more and more universities, schools etc. use. You can upload a paper and it is checked for plagerism and a report is delivered on how much of the text matches.
MISSION: Now, the tough part is, I'm not sure whether this is a service, software, or even if it is attainable. If anyone can find this, there is a substantial REWARD.