[ame=http://www.youtube.com/watch?v=feeOtWGZg1o]YouTube - ‪Activate Flash Like iOS 5 With LockFlash Cydia Tweak‬‏[/ame]
LockFlash is a tweak that will add an iOS 5 looking feature, to your older firmware devices. In iOS 5, you are able to double tap the home button on your Lockscreen to bring up an "open Camera" option. This tweak does a bit of the same, but instead turns on your LED flash. This way you can have light where there is no light, find what you need, and get out of there! Don't be afraid, FlashLock only looks like an iOS 5 feature, it will work for 4.3.3 and below too! Try it out, it's free in the Cydia Store.