Captain Chords - Write chord progressions in your favorite DAW
IsoPad - IsoPad lets you use your Windows tablet to play electronic MIDI instruments.
Odesi - ODESI is a music sketchpad that exports your projects to Audio and MIDI.
TouchDAW - Full-featured DAW control and general purpose MIDI control app.
Cthulhu - VST MIDI-FX plugin for harmonic inspiration
Navichord - Intuitive chord sequencer and MIDI controller for iOS