Making live electronic music more ‘playable,’ and be less of a ‘press play’ type performance is a big topic in the EDM community, and I can see the iPad playing a huge roll in how it all plays out. The touch screen allows artists, like DJ Zinkus, to experiment with different interfaces and layouts, and not have to design or buy physical hardware controllers. Apps like Lemur (and MIDI Designer) allow artists to easily design and develop their own experimental instruments/controllers for use in a live setting, and thanks to the iPad’s touch screen, the possibilities are endless. It also transforms the device into an extremely playable instrument, if you’re open to the idea of using it as one. The size of the screen is really the only thing holding the iPad back at this point, but who knows, maybe we’ll see a giant iPad one day.
Shout out to the developers of the Beatsurfing app for iPad – they’re really pushing this idea out too.
Lemur 
MIDI Designer
MIDI Designer Lite
touchAble
