I Am T-Pain from Smule is now available for free in the App Store for a limited time.

Sing into the mic on your iPhone and I Am T-Pain will record your voice and give you the T-Pain effect. Then, with a single button, share your song over email, Facebook, or Twitter.
Receive 9 tracks free with the app
Look out for brand spankin’ new beats from the hottest producers released in the app. The first 200 to download them get them for free!
Sing any song in your iTunes library with the T-Pain effect
Get previously unreleased T-Pain original beats
Purchase additional songs like On A Boat, Buy U A Drank, and 5 O’Clock directly from the app
Use Freestyle mode to sing with the T-Pain effect without background music
Create your own T-Pain effect videos