Whenever you find yourself in a dark place, chances are you don't have a flashlight on your person, but you do have an iPhone. For that reason, it's a good idea to install a jailbreak tweak that allows you to easily use the iPhone's built in LED flash as a flashlight.
There are already a handful of decent flashlight tweaks available on Cydia, but this latest one called Torch is one of the better implementations. Torch is a tweak that places an easily accessible flashlight button on your Lock screen that will enable or disable the LED flash.