The guys that brought a virtual flame you can actually blow out uses the same audio processing engine for entirely different purposes.

Smule, the guys that brought you Sonic Lighter - a virtual flame you can actually blow out - is offering a new title in the iPhone app store. Called Sonic Vox ($0.99, available here), the app contorts your voice while you are talking, turning the iPhone into (in the words of Smule) "a magical Microphone of sorts." All you need to do is swipe your finger across the iPhone's touch display to get the various real-time vocal effects.

Here's a video showing Sonix Vox in action: