Android: Even if you have a few dozen apps installed on your phone, you probably only use a handful of them every day. Hangar keeps track of the apps you use the most and adds them to your notification shade or a homescreen widget.
When you first install the app, you'll see the most recently used apps. As you continue using it, the shortcuts will be replaced with the ones you use most often and spend the most time in. If you would prefer to have more control over your shortcuts, you can also try previously mentioned Quickly.