Tweaks like NCSettings and Auxo are great because they provide quick access to a variety of toggles on the iPhone. One of these is the flashlight toggle, which easily turns on and off the LED flash on the back of the device. Thing is, with both of these methods you're still fumbling around in the dark preforming several steps to get to the flash toggle before you can even turn it on.
With the free tweak SpringFlash, you can assign any Activator action to the flash, making your iPhone a flashlight on demand. Once installed, SpringFlash defaults to using a double-press of the sleep/wake button as a flashlight on/off switch.