We are using opentabs at hackerbeach. This means that anybody can ask anybody else to tab their drinks and food, or other things we need to pay. This is an experiment in decentralized banking that is both practical in itself (one person goes to pay the bill and just tabs what everybody had), and it is meant to obtain experience with how decentralized banking can work in practice. Ask Basti for the spreadsheet and webform links if you want to participate! 🙂