Among many music apps, here are the most preferred.Pairshare app, costs $99, allows you to stream your live music to a friend's iPhone or iPad over bluetooth.
Shazeem, a free app identifies what song is played. It provides preview and allows to buy tracks on iTunes. I am T-pain, Tune -in radio and Tunemark Radio costs $99 and comes with its own merits.
The remaining apps such as Anthem music videos, Slacker Radio,Iheartradio and Tunewiki comes for free of cost.