First, if its not in the iTunes store, its not getting onto your touch unless you jailbreak it. There are some useful features out there for it as a remote but you have to be running VNC in another machine. There are some
DMX calculators out there. There is also a level app which is kind of cool. I would say that this thing is extremely useful if you have it with you at all times, if you have to go get it every time you use it I think it would be a waste. There is an artnet app for it. I don't know if I would want to view a plot on it, that could be a bit out of the realm of what it can easily handle. Personally, I would buy an eee pc or a cheaper notebook to do the above items. Unless you need the portability, I think you would be much happier with an actual computer.