TinEye is a reverse image search engine. You can submit an image to TinEye to find out where it came from, how it is being used, if modified versions of the image exist, or to find higher resolution versions. Check out this video:
TinEye is the first image search engine to use image identification technology rather than keywords, metadata or watermarks.
TinEye is from Idée Inc. The Toronto based firm develops advanced image identification and visual search software.