Pixiple - Find images similar in pixel and/or metadata content
Duplicate Media Finder - Duplicate Media Finder locates and deletes identical files and similar media
ImageDupeless - ImageDupeless - the program for search/find of the similar images (duplicates) in the large galleries (collections).
VisiPics - VisiPics does more than just look for identical files, it goes beyond checksums to look for similar...
Awesome Duplicate Photo Finder - Awesome Duplicate Photo Finder is a free powerful tool, that helps you to find and remove duplicate...
SimilarImages - A free application designed to find similar images (duplicates) on your HDD.