First-time developer Dmitry Klochkov has released a Universal iOS MIDI instrument for playing chords.
ChordUp iTunes Description:
Chord playing musical instrument and MIDI controller.
Play instantly any of 108 available chords with no pre-configuration. Play easily any chord pattern: bass and chord, strumming, arpeggios, power chords, etc. Play your favorite synth or sampler with MIDI mode.
- 108 available chords (9 chord types for each of the 12 keys).
- 4 octaves range for a selected chord without using octave shift buttons.
- 8 octaves range with octave shift buttons.
- 9 embedded instruments.
- Smart sustain. With the sustain enabled, when you switch chords, only the notes of the current chord that don't belong to the next chord are muted.
- Adjustable buttons on iPad.
- Virtual MIDI and Wi-Fi MIDI support.
Here's an epic demo of the app playing a brass ensemble in SampleTank. Other examples are available on YouTube.