Here’s a pretty cool tool that I bumped into. Might just be the justification I need to buy an iPad , that and the fact that I want to do iOS / RubyMotion development targetting iPad.
Here’s a video showing how its used with Logic Pro. BTW, you can also not only use it with a number of DAWs but also virtual synths and just about anything midi. It does though come as a official Logic Pro control surface i..e it will just work.