If you live in Finland you must have seen those K-plussa bonus cards. You have to carry card in your wallet and show it (via NFC technology) when buying something.
Yesterday I decided to download beta version of K-plussa card app for Android. Take a look. It's in the Play Store: https://play.google.com/store/apps/details?id=com.plussa.plussacard
Off I went and tried newly installed app. I placed my phone side by side with NFC-based device in the nearest K-market. And indeed I got my bonus. If your phone doesn't do anything move phone a little bit so that NFC circuit (of your phone) is in the right position.
I guess the only downside is K-plussa card app is always there in the background of the memory of your phone. And NFC is also always on draining your battery (?).
I'm happy with K-plussa card app. One plastic card less in my wallet!