Just messing with Tap Dj, mixing app from Installous.
Best dj app ive found so far, iPad definitely has this area covered... But iPhone a little slow on the uptake.
But this let's you load your own tunes and get "hands on" so you can cue, scratch etc
Decent for anyone who likes mixing, only drawback being the pitch/speed changing needs to be more refined, other than that though... It's good fun!