Songza

Songza plays the right music at the right time. The app is free, and allows you to listen for as long as you’d like. The app differs from other radio streaming services in that it chooses songs based on mood or activity rather than similar artists. If you’re working out, for example, it’ll play songs to match that activity.

If you’re feeling tired, sad, happy, or some other emotion, it’ll play songs to match your mood.