A free app for Android, by AlienGod.

Take a selfie in low light without a front flash on your device? Due to the front flash camera, it is now possible!

The Front Flash Camera app actually improves the appearance of selfies by illuminating the subject and eliminating facial shadows. It is a small light that is actually rather soft and less obtrusive than the conventional flash on a camera.

This is the same rationale behind why professional photographers reflect light using large mirrors and white screens, or utilize direct defuse light to improve the appearance of portraits. 

Filling in with additional light can enhance the appearance of a photograph, thus the Front Flash Camera also functions.