Flowkey - The easiest way to learn piano with your iPhone or iPad
Mightytext - Send & Receive SMS Text Messages from your computer. Sync'd with your Android #
Yousician - Learn to play music at home, at your own pace
Zeplin - Collaboration app for UI designers & frontend developers
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
ActiveWords - Auto correct on steroids