Though there are many methods for using custom iPhone ringtones, few provide the simplicity affored by Ambrosia Software's iToner, which has now been updated for compatibility with iPhone software/firmware 1.1.3.
With this $15 tool, you drag and drop MP3 or AAC audio files on iToner?s window, click the Sync button, and the items are automatically moved into the iPhone?s ringtones section. It has no method for selecting a portion of the track ? you?ll need to edit the file beforehand with a sound editor (like Fission).
Other enhancements in the new release (version 1.0.6) include: support for .mp3, .mp4, .wav, and .aif files; intelligent audio processing for added ringtones; French, German, and Italian localizations and some bug fixes.