Plagiarism.org

This site offers an on-line tool that help instructors detect plagiarism. This particular tool only checks against on-line material and papers put into the database by other instructors. This technology can detect plagiarized papers that contain substituted words or sentences. A paper's contents are uploaded to the site for remote processing. As with all such systems, it should be used with care as the consequences of a wrong charge are high. For instance, one system called a paper plagiarized when it matched the paper the student put on-line.

http://www.plagiarism.org/