AudioTag - AudioTag.info — is a free music-recognition service.
Dupin Lite - Dupin Lite is your iTunes duplicates manager.
Shazam - Shazam is a mobile app that recognizes music and TV around you.
iTunes Duplicate Song Manager - iTunes Duplicate Song Manager with Folder Watch removes iTunes duplicates in Windows and Mac OS X.
ACRCloud - Automatic Content Recognition (ACR) cloud services for Audio Recognition ( identify music, ads ), Broadcast Monitoring, Second Screen, Copyright Protection.
Tune Sweeper - Show duplicates in your Music library. Automatically select which duplicates to keep and delete based on your preferences. Remove duplicates with one-click from your iTunes or Music app library.