Nice job. Very clean interface.

Consider adding a playback feature for the chord progressions as well as the musical modes, so people who are unfamiliar with certain ones can get a feel for how they sound.

Also any particular reason for naming it after the FF6 yeti? :)

Tried the rhythm trainer : it feels weird, some rhythms (the cuban claves for example) seem wrong. Also the metronome doesn't sync with the rhythm, which makes it quite hard to differentiate offbeats from quarter note for example.

I like the UI though, and the omnipresence of the metronome is cool.