Mixmeister Scratch - iPhone Disc Jockey Apps

“MixMiester Scratch let’s you perform a scratch anywhere, anytime – even right on top of any song in your iPod Touch or iPhone.” And, it’s true. Just install Mixmeister Scratch on your iPhone, and use the included “scratch-tracks” (basically random music or sounds that work well for scratch sounds) to annoy your co-workers. Mixmeister Scratch allows you to scratch the day away with the included scratch tracks, or you can overlay the scratching sounds on top of songs from your iTunes library.
Read more details and demonstration video > here.