DupeNuker

Uses the CRC32 algorithm to identify duplicate files on your system. You can then review the list of duplicates and decide whether or not to delete them. DupeNuker keeps a database of every file it examines, so new files can be checked quickly. New files do not have to be checked against every other file on your system, but only to the CRC32 "fingerprints" in the database, which is very quick. DupeNuker is designed for people who collect large numbers of files. For example, if you download large numbers of pictures or MP3's, DupeNuker can very quickly identify which files you already have in your collection.