The App Store and Mac App Store are home to plenty of apps for novice and pro DJs alike. Algoriddim's djay 2 (read our review) and Native Instruments' Traktor DJ are among the finest examples of how a tablet can be used to double as a virtual turntable for mixing tracks in real-time.
I've seen a number of DJs hook up their iPad to pro equipment and mix tracks from their iTunes library as if it were second nature. To be perfectly clear, I suck at DJing and have no interest in it.
Those who dig DJing, however, are advised to take a look at the just-updated djay 2 for the iPhone and iPad or take advantage of a time-limited discount on Traktor DJ for the iPhone and iPad. I also mention another notable discount on a similar app, Cross DJ for Mac. Jump past the break for the full reveal...