Ringtone Designer Pro for the iPhone lets you make your own custom ringtones from your iPod library. Simply select a song, and select a short clip you’d like to use for a ringtone. The app costs $1.99 on iTunes and here is a video tutorial [iTunes Link]:
So if you were one of those tired of all the hacks and efforts to get custom ringtones on the iPhone, there you go officially!
(Note: Ringtone Designer allows you to make ringtones anytime, but you need to sync with iTunes to get the ringtones into the Settings section of your iPhone. Don’t worry. It’s quick, easy, and we even have a video to show you how.)
The iPhone Help
The iPhone Help