I've always been a bit dumbfounded that flashlight apps exist for the iPhone (actually, not that they exist, but that people download them). The main reason is that whenever I need light, I need it quickly. Having to:
- wake my phone
- unlock it
- input a passcode
- locate and launch an app
Unfortunately, when waking the iPhone, it only remains awake for a few seconds before going dark again. However, if you slide the slider to unlock it (even if you are prompted to input a passcode), it stays lit for a whole minute before sleeping.
So I've found that the fastest and most convenient way to use the iPhone as a flashlight (albeit a simple one) is to:
- Click the 'sleep/wake' button
- Slide the slider
[crarko adds: I tested this, and it works as described. It's good if you need the lighting briefly. The obvious reason for the flashlight apps is that sometimes one needs the light for more than a minute. And sometimes they operate as tethering proxies. (That's a joke, folks.)]

