Shazam - Shazam is a mobile app that recognizes music and TV around you.
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.
Acclaimed Music - Acclaimed music is a top music recommendation tool that showcases the most popular song based on which is currently topping the Billboard charts and provides links to the latest music news.
iTunes Duplicate Song Manager - iTunes Duplicate Song Manager with Folder Watch removes iTunes duplicates in Windows and Mac OS X.
Spotify - Map shows when two people play same song at same time
SongGenie - SongGenie analyzes, identifies and repairs your mp3 tags and names.