RapScript - RapScript is the fastest-growing word-machine that is specially designed for freestyle rappers.
Sampulator - Make (and record) beats on your keyboard
AR Lyrics - Lyrics in the air!
Auxy Music Studio - Auxy brings real music creation to iPhone in a simple and inspiring format.
The Art of Rap - The Art of Rap is a free to use mobile application that allows you to create and record your rap movies to share it with others.
Ramsophone - A generative art/music machine. (Be sure to refresh!)