VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
Flowkey - The easiest way to learn piano with your iPhone or iPad
AIMP - AIMP : Free Audio Player : Официальный сайт программы
Yousician - Learn to play music at home, at your own pace
foobar2000 - An advanced freeware audio player for the Windows platform.
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.