Android: Android's open nature is brilliant, but some things can't be tweaked without rooting or installing Xposed. One of those elements was the navigation bar of Home, Back and Recents button, but Navbar Apps just changed that. This simple, free utility lets you set a custom background colour for the navigation bar, or tell it to match the colour of the running app. You can also add a custom image of your own for a little added personalisation.
Navbar Apps also adds widgets to the navigation bar, giving it more functionality than ever before. Currently, you only get a battery widget, but the developer said a music widget is coming soon.