Flashlight (torch) widget, supports Android 4.0 (ICS) and Android 4.1 + 4.2 + 4.3 (Jelly-Bean) and even 4.4! (Kit-Kat). If your phone doesn't have a camera flash, it will turn your screen to bright-white to illuminate as much as possible without a flash.
To use: long click an empty space on your desktop, choose 'Add widget', and then choose the 'Flashlight widget'. An on/off switch will be added to your desktop