The TinEye search engine, developed by Idee and due to be released out of beta later in September, allows users to search for an image by uploading a picture rather than searching by keyword. The search engine will conduct a pixel by pixel search to identify all instances of the image (even if the image has been digitally altered). The primary use of the search engine may be copyright enforcement; however, it may also be useful in identifying image creators so that proper attribution can be provided.
Thanks to the Law Librarian Blog for information on this new resource