Well the main usage people think of is payment. Contactless banking cards are becoming more and more common and a NFC phone can act like a contactless bank card. This means that when you are in a shop and ready to pay, rather than getting your standard plastic card out you can put your phone near a payment ‘reader’ and complete the payment.
The next thing that is commonly talked about after payments is access control or simply door security. Many offices and public spaces have contactless readers that keep doors locked and authorized people can use a contactless card to open the door. Again the NFC phone can play the role of the door entry security card and open the door, when it is place in the field (the F in NFC) of the door reader.
This being said (or written), there are many things you can do with NFC, some of which we have candidly listed here.