Interactive Midi Player, watch the notes being played in real-time, display the harmonica tablature for either chromatic and diatonic harmonicas, change the key and even the tuning (custom tunings included), slow down and loop play the tune or part of it.
Watch the words and sing along for karaoke midi files.
Simple editing features, like transpose, volume change, midi instrument program change, delete notes or tracks, strip out pieces of the file, and save back to midi format.
Printing, etc.