49% of people exposed to Doritos ads on XBox LIVE subsequently went out and bought Doritos

"Doritos’ ‘Unlock Xbox’ competition invited fans to capture the essence of the snack in the form of a Doritos Xbox LIVE Arcade game with the opportunity to win a $50,000 gaming consultant project. The campaign put the votes of Xbox LIVE users at the heart of the contest, driving far-reaching engagement and ensuring huge interest in the final Doritos games. The field was narrowed to eight by an expert panel of judges, and then pared down to three by the votes of Xbox LIVE visitors. After a pitch at Microsoft headquarters, the two finalists (Doritos Crash Course and Harm’s Way – by Doritos) were launched for free download on Xbox LIVE, with gamers voting on their favourite.
Key results:
Throughout the contest, Unlock Xbox delivered exceptional engagement levels
The winning game became the fastest downloaded Xbox LIVE Arcade game in history with over 1 million downloads in the first two weeks
Over 50% of those exposed to the Doritos ads on Xbox LIVE clicked to learn more about the contest
40% voted for their favourite Doritos Xbox LIVE Arcade game
72% took action after seeing Doritos advertising on Xbox LIVE
24% told friends about the Doritos Xbox competition
49% went out and bought Doritos"

Source:  Case study from Microsoft Advertising (UK), 4th July 2011