Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.Download on the App Store
Audiobus is the app that makes the rest of your setup better.
Midi Breakout Box video
I just uploaded a video that shows a low cost, light weight app that is pretty useful in saving patches for multitimbral apps such as Soundcanvas and BS-16i. I've tested it with both of those and it works well. It doesn't work with Auria and Soundfont Pro though, but I imagine there are other apps that respond to PC messages that would also work with it.