If you're worried about losing your iPhone, you can take out a bit of insurance by adding your contact information to its lock screen. That way, if you lose it, whoever finds it (assuming he or she is a good Samaritan) will know how to return it to you. MacOSXHints.com reader Alain Duffieux wrote in to tell us how he does that in iOS 4:
First, you need an image for the lock screen's background. You can use a photo you already have or download one from a site like wallpapers4iphone.com. Wherever you find it, just make sure it's cropped to 320 by 480 pixels. (You can do that in Preview by selecting the portion of the image until it's the right dimensions, then Tools > Crop or Command-K).
Open the cropped image in your favorite photo editor and, using its Text tool, overlay the image with some text, something along the lines of
If found, return to, along with your name and phone number. (Make sure you don't put down the number of the iPhone!) Save the picture wherever you like on your Mac.
Next, open iPhoto and import the image. (You can do so by dragging the photo from your desktop into the iPhoto window.) Then, open up iTunes and plug in your iPhone. Select it in the left-hand sidebar and open the Photos tab. There, make sure the Sync Photos from iPhoto box is checked and that the event or album containing the image you just created is set to be synced. That done, sync your iPhone.
When the sync is complete, open your iPhone's Settings app and go to Choose Wallpaper. Find and select the image you've just created, then hit the home button. From now on, if someone finds your phone and turns it on, they'll see the lock screen—with your contact information on it.
If you're still using iOS 3, the only difference is that, to add the wallpaper, you go to Settings > General, then tap the album in which your wallpaper resides to add it as your lock screen.