If you haven't seen it yet, there's a Coke Zero promo on YouTube for the new James Bond movie, "Skyfall". And it racked up millions of hits on YouTube over the weekend.
Basically, they put a vending machine in a train station, with a video message on it telling people they had 70 seconds to get to a certain train platform on the other side of the station. Then they put obstacles at every turn...If they got there in time, they won free "Skyfall" tickets.
(They start running at :28. The YouTube description says the people were, quote, "unsuspecting train passengers," but it kind of seems set up.)