NFC enabled digital wallet.
If anyone can pull this off it would be Apple. Okay here goes:
Apple creates an iWallet app, I would put it on my dock. iWallet basically has cards that you can flick through in cover flow style and see some basic details below it. The cards can be used through NFC. To get a card into the wallet, you create an app which adds a card to the digital wallet, and the app handles more advanced functions.
Two examples:
Public Transport
I live in Perth, Australia and we use the smartcard system for our public transport, similar to the oyster system in the UK. The company is called Transperth.
Transperth could create an app and it would add the card to the iWallet app. To 'tag on' I'd open the iWallet app, key in a 4 digit pin if required, navigate to the card and hold it to the tag on device. From there, I could tap an icon and go to the Transperth app and do things like check timetables, check my route/location, top up my credit etc.
Banking
Banks could do something similar. We've all heard of PayWave/Pass? Commonwealth Bank of Australia have created an app and are selling NFC iP4/S cases to do just that. The iWallet app simply provides a quick access point for one of the features already implemented by this app - perhaps even only the "most used card" would show up.
Future
The future of this would lead to not needing a wallet. People would still own one and carry real money of course for a long time, but if I want to just go down the road and pick up some groceries, I don't *need* my wallet.
In the future, states/countries could issue ID's to phones even. Police would need an NFC reader to confirm identity perhaps, but nothing more than what transit guards already use. It would even allow for licenses to update information such as expiry, name, photo etc quickly and efficiently.
Personally, I think phones with NFC readers would be a good thing in emergency situations. I would appreciate a medic or police officer to be able to check my phone to work out who I am in a simple pass of a device, without needing to know my password (with appropriate authentication of course).
Of course, there would have to be a standard eventually so that any phone can do it, but like I said, if anyone can do it and start the ball rolling, Apple can.