I'm really digging what VaymerMedia did with Gowalla and the New Jersey Nets. For those that missed out, essentially VaynerMedia paired Gowalla and the Nets together and hid virtual tickets in locations around the tri-state area. When a user checked in to a participating location, they were able to grab the virtual tickets and then exchange those for actual tickets to a Nets game. They just had to show that they had the item at the Izod Center and they were given admission. But the fun didn't stop there. Guests who claimed their tickets were able to check-in again with the potential to win jerseys and other prizes.
I recommend reading through the case study if you have a chance. I think this was a very clever concept and could definitely be expanded upon. I like the exploratory nature that this involved, kind of like a finding a golden ticket in a Willy-Wonka-and-the-Chocolate Factory kind of way. There are a lot of low-hanging fruit use cases for apps like Foursquare and Gowalla, but this is a good implementation that could work very well for live events. I think one of the key insights was that these seats were not going to be filled if they didn't run this promotion. That means people came and spent money on parking, food, merchandise, etc. that they likely would not have spent at all and they may in fact have spent more than normal because they didn't pay for tickets. The concessions and merchandise are generally high-margin items as well. So for events, this is definitely something worth looking into if you put on concerts or sporting events or other performance-based activities.
Anywho, very interesting.