While the iTunes Application store does have plenty of freebie applications for lighting up your iPhone, there isn't a good solution for lighting the backside, especially useful for when you are taking pictures.  Over on iPhonexe Blog user Joe has come up with a mod'd solution.  By taking four LED lights, some wiring and a switch he was able to make his own camera flash for the iPhone.  Fairly simple wiring makes the LED's powered by the iPhone.

If you're up for modding out your iPhone to take better pictures, check out his entree at the iPhoneexe Forum.  You can also see how to make the camera zoom to different focuses in a MacMod news entry from August 2008, the iPhone Camera Focus Mod.  With this combination, you won't need to buy that new camera, just bring your iPhone to the next photo shoot!