I recently built the app for Style Aid whilst working for Gatecrasher Advertising.
A mobile game of Pass The Parcel was played on the event night (27th of July 2012), where 15 electronic parcels will were passed around the room and won at random. Users who had downloaded the app and then register. Push Notifications using UrbanAirship were sent as each parcel was sent around.
Guests at STYLEAID had the opportunity to have their very own red carpet moment. Photographs were taken and uploaded into a CMS and then users could share on facebook or twitter.
I used .NET MVC to handle the requests from the app in a REST methodology and a simple windows service was created to change update who had the parcel and to send the push notifications.
More info about the event can be found at the West Yahoo website