From Musicsoft Arts:
DJ Mixer for iPhone is the only iPhone DJ mixer that allows you to beat match your tracks without affecting the playback pitch and to quickly skip around your tracks to find a good spot to mix using a unique visual music display and an auto BPM detection. Use DJ Mixer for iPhone to quickly play a continuous mix of your music with smooth fades between songs or to mix your tracks at a party or just for yourself. DJ Mixer for iPhone turns your iPhone or iPod Touch into a powerful interactive music mixer that lets you play your music at a party like a pro without using expensive and complicated hardware and software.
What's new in this version:
Version 1.7 has direct music transfers from OS X.