Speaktone creates ringtones with the system text-to-speech synthesizer.
Add more voices through System Preferences / Speech. Apple has provided a wide selection of different languages and dialects.
You can control the speed to create even funnier ringtones!
What’s new in version 1.3
Updated on Mar 22 2014
Version 1.3:
Now supports creating ringtones from any media files, including videos! Just drag and drop them into the app and it will automatically create a usable ringtone and present it in iTunes.