TinEye (http://www.tineye.com http://www.tineye.com): a 'reverse image search'. You upload or link to an image and it finds you other copies of that image on th

TinEye (http://www.tineye.com http://www.tineye.com): a 'reverse image search'. You upload or link to an image and it finds you other copies of that image on the web. This is something you absolutely can't do via google, and is surprisingly useful, for example to find uncropped or pre-photoshopped copies of images.