Credit This app would not have been possible without the generous help of NetMage, who showed me how to control the brightness.
Description Really, you want a description? Well, ok: Flashlight flips your iPhone's brightness up to full, and displays a full screen white rectangle. Slide your finger up and down to change brightness. Double tap exits. On exit, your user settings for brightness are restored (well, autobrightness might not work perfectly).
Disclaimer You should be aware of one more thing though: this is obviously a hack, and probably goes beyond what will ever be a part of any public API. It has also NOT yet been tested (to my knowledge) on the iPod touch.
As such, it does contain the potential to completely destroy your iPhone or iPod touch. It might even cause a fire, or some other sort of horrible damage. There's no warranty of ANY kind included with this app. Use at your own risk.