Magic Tap has developed an iPhone application that lets you do just that.
Sells for 99 cents in the Apple App Store. It will make it look like you just got a call from your mother, cousin or even President-elect Barack Obama-anyone you want. You can customize the caller name or number, decide when to receive the call, change the wallpaper for the caller ID and set the phone up to ring or vibrate.
Fake Calls does not actually initiate a call so no airtime charges apply. Magic Tap also says it will donate 10 percent of earnings from the application to several unspecified charities.
You have to hand it to Magic Tap for developing an app that is novel and useful, although you have to wonder if Fake Calls will end up being the perfect excuse or a source of never-ending paranoia on blind dates. [Source]