Berg design agency have come up with this receipt to demonstrate the kind of information systems that till point machines can tap into, from Google Calendar to real-time product sales. 

If we can't receive digital receipts via a mobile device to minimise paper waste just yet, then this at least makes them more functional and a bit more joyful. 

http://berglondon.com/blog/2011/06/02/icons-rethink-turning-receipts-into-paper-apps/