Palo Alto, Calif. startup Smule doesn’t just develop some of the coolest iPhone applications (including musical app Ocarina) — it has also put together the best contests to promote those apps. Its latest the “I’m on a Boat” competition to promote its “I am T-Pain” iPhone app.I am T-Pain allows you to transform your voice with Auto-Tune technology, giving your singing or rapping the distinctively mechanical tone heard in songs by hip hop musician T-Pain and others. Now Smule is trying to find the most talented app users (and to promote the app too, of course).Participants record their performances of “I’m on a Boat” (a song featured in a Saturday Night Live skit guest starring T-Pain) and upload the footage onto YouTube. Then the company uses what it calls “a proprietary T-Pain induced Smulean algorithm which combines views, ratings, suggestion of some musical talent, and lyrical inspiration,” to choose one finalist per week for 10 weeks, then a grand prize winner. Each finalist wins prizes, and the top contestant gets $5,000 and a “Big Ass Chain” (weighing 10 pounds, apparently) to match T-Pain’s.Smule is also cutting the cost of the app to tie into the promotion, from $2.99 to 99 cents, starting this afternoon and ending on Saturday night. Not that sales haven’t been strong already — I am T-Pain was at the top of the App Store charts the weekend it came out, and Smule says it has sold 300,000 copies, leading to 4.1 million performances.