QR stamps

Croatia’s ‘2011 Postage Stamp Day’ marks the twentieth
anniversary of them, er, using stamps. The
Croatian postal service is celebrating with clever QR-coded stamps.
When you’ve sent a letter you can receive instant delivery confirmation,
as well as tracking all the places it’s passed through on a dedicated
mapping site. Making up for lost time in impressive style.

http://www.qrmarka.posta.hr/en/