RGB Light is a useful and simple to use app that turns your device in a RGB colour picker and a light!
Double tap on the screen to choose a colour with the intuitive interface. The selected coulour will be then showed fullscreen and also given as an RGB code in hexadecimal value (for example: #FFFFFF for white, #FF0000 for red) that can be copied to the Clipboard.
And, because this is also a light, tap on the top right flashlight icon to turn on the device led!