Shazam is a classic mobile app. In fact, I would be suprised if there were any mobile users left out there that did not have it installed. Given this is the case, I am likely preaching to the converted, but if you are one of the remaining few who have not caught on - install Shazam now.
In short, if you are ever listening to a song and wondering what is it, who it is by, what the lyrics are, etc, simply boot up Shazam and in a number of seconds the song name will be on the screen and the lyrics will be scrolling down your display in time with the music. Shazam = a great app. Classic.
In the words of the developer:
Hear a song you don't know? Shazam identifies it instantly. Free and Unlimited.