Riff Raters is an iPhone app that lets musicians record and share their musical riffs with the world. Listeners rate and comment on the music they hear, helping to determine which riffs make the Top 25. Riffs are “short repeated melodic phrases,” usually lasting no more than twenty seconds – like a musical “tweet”. All instruments and musical styles are welcome and musicians can record original riffs on their iPhone/iTouch with any instrument. Even if you don’t have an instrument to record a riff, you can rate and comment on the riffs you hear, browsing by instrument, genre or musician. This app is priced at $1.99.