ReturnMeTo makes it easy for someone finding your iPhone to return it to you. The application icon is designed to encourage someone to touch it, even someone who is unfamiliar with the iPhone. I keep it in the upper left hand corner of my Home screen to pique the curiosity of whoever finds it.

When the application is launched, it displays the phone number you want the person who found your iPhone to call.

You can also make the phone number display, even if your phone is locked, by using ReturnMeTo as your wallpaper.
1. While holding the Home button, press and release the Sleep/Wake button at the right at the top of the iPhone
2. The screen will flash and you will hear the same sound as when you take a picture using the camera
3. Go to the Settings application, select Wallpaper, and then select Camera Roll,
4. That will take you to your Photo Library where you can scroll to the screen shot you just took and select it.
5. Select Set Wallpaper from the dialog that appears and you’re done.

When you do it this way, the number is available even if your phone is locked.

To enter a phone number the first time, you touch in the text field, but after that you need to know the location of a super secret button that will allow you to change the number. Between you and I, it is the telephone image in the center of the page. Touch that button and the text field will be enabled. That is to avoid any accidental changes to the number.