Songlio - Free musical guessing game: race friends to name that tune
Hum - Songwriting for iPhone
SongPop - The world's biggest music trivia game. Now even better.
Songcraft.io - A platform for songwriters to write, organize & collaborate.
Rock On! - A song pop adventure - music trivia awesomeness
Horucco - Horucco is an cloud based app for musicians, songwriters, producers of every skill levelExplore chords and discover related chords on the fly.