Are you a little envious that the iPhone 4 has an LED flash?
If you're still carrying an old iPhone 2G/3G/3Gs and wish you had a flash, consider the iFlash — a small LED flash dongle.
The iFlash connects to your iPhone's 30-pin port and has an on/off button for it to function as a camera flash or as a regular flashlight. I know, I know, you probably already use your phone's screen as a flashlight like me, but a proper flashlight will always be better. God knows how many times I still bumped my head in the dark while using my phone's screen as a light.
Most people will use flash in the dark, causing their pics to become washed out. What they should be using it for is "fill flash" to bring out the details from the shadows when it's sunny outside. Just a little meme to help you take better photos next time you're out and about.
The iFlash will cost ya $40. It's small, has a little doohickey to strap it to your iPhone's 3.5mm audio jack and perfect for your niece or nephew come the holidays.