I developed a music theory MIDI generator with all scales, all chords, all keys including the past 100 years of chord progressions used in popular music (ordered by most famous to very dissonant ones). You can find the beta MIDI chord pack here:
https://www.dropbox.com/s/9l6guk9jdz5mpe6/MidiTheoryPack_bet...
With these progressions you can easily create a basic harmony for your music and with the scales and chords you can diversify them and make them actually great compositions.
But please don't share this too much yet. I'm still working on that and will release it Open Source very soon after a refactoring of the code. If you are good in music theory. Please send me suggestions here in the comments. I'll keep you posted