Allows adding AnyRing ringtone such pieces as the iPod Library as well as the selection range (star/end point).
Does not require converting audio files;
Accept as sources: iPod Library, Record Your Own (with microphone device), Received Ringtones (Bluetooth), Youtube;
Allows assigning a Ringtone per Contact;
Allows you to set music to Ringtone, SMS, Email;
Supports version 4.0 or newer iOS;
The application require Jailbreak and is available in Cydia for the price of $ 3.99. There is a 10-day trial version.
Mp3 tracks can be used as a ringtone and a manual conversion using iTunes if you are adept at various variants.