Mixxx - The most powerful free DJ software in the world.
Flowkey - The easiest way to learn piano with your iPhone or iPad
VirtualDJ - Virtual DJ Software - MP3 and Video mix software for DJs
Yousician - Learn to play music at home, at your own pace
Guitarix - Guitarix is a simple Linux Rock Guitar Amplifier for https://alternativeto.
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.