Virtual Audio Cable - Ever wanted to record your speaker output? (loopback) This is for you.
Musicope - The Piano Game. Contribute to oldrich-s/musicope development by creating an account on GitHub.
Loopback by RogueAmoeba - Get all the power of a high-end studio mixing board, right inside your Mac!
Piano Time - Piano Time is a multitouch piano with 36 visible keys and 4 selectable octaves.
JACK Audio Connection Kit - JACK Audio Connection Kit|Home
Linthesia - Linthesia is a game. A game of playing music! You only need a MIDI file