Freeware - Autotalent Monophonic Pitch Correction Plugin

http://tombaran.info/autotalent.html

Autotalent began as the result of a week of recreational signal processing in May 2009. It's a real-time pitch correction plugin. You specify the notes that a singer is allowed to hit, and Autotalent makes sure that they do. You can also use Autotalent for more exotic effects, like the Cher / T-Pain effect, making your voice sound like a chiptune, adding artificial vibrato, or messing with your formants. Autotalent can also be used as a harmonizer that knows how to sing in the scale with you. Or, you can use Autotalent to change the scale of a melody between major and minor or to change the musical mode.