Inspiration from http://www.canberratimes.com.au/act-news/canberra-oktoberfest-organisers-apologise-for-lines-20161030-gsdx6e.html
Basically this is a card that everyone gets at an event that doesn’t want to do cash or credit-only. They get the card, use their phone to load some money onto it for use in a “cashless” scenario like octoberfest. The cool part is that when you put money on the card, you can specify a charity that the left over money goes to when the event is over. This both encourages users to spend everything they’ve put on their card at the event, and does a good thing for society and makes everybody feel better.
The extension to the idea is for more general usage at conventions: Imagine CES or some other trade show. Everybody has this card, users can setup profiles, and at each booth users can swipe their card to say they have visited. This means event organisers can track flows, and get a bunch of data to use. Users get a mini social-network. They can rate booths and can see other users who have similar interests to them, and perhaps IM them to meet up to discuss.