People keep asking about a PoS system. All the proposals involve the users having expensive mobile phones or some kind of specialised electronic equipment. This does not help normal people, people without phones or the developing world.
I hacked this up for a bar inside a social centre in Milan (
http://www.macao.mi.it/ ):
https://github.com/genjix/macaoExplanation:
User has 2 QR codes. Imagine having 2 credit cards with a QR code on them and a swivel hinge on them. The QR code on the top card is your public unencrypted receiving address. Your rotate the card, and the one inside is your private encrypted sending wallet seed (used to create your private key).
The bar then has a terminal with the software running (check the subdir called 'wallet'). You scan your private QR code, enter your password and are presented with a menu:
Amount: [_____________0.00_]
* Pay to bar
* Pay to QR code
* Enter Bitcoin address
You can type how much you want to send, then click pay to bar. Or you can scan someone else's public QR code.
This is inexpensive and easy way to get people into Bitcoin without requiring any technology on their part. You can issue accounts for people and print them out then and there on the spot. People can send to other people, and mobile phones can send to their public QR code. To make payments, they use the terminal. Or they can go home / on a phone and enter the seed there and continue using the wallet.
Simple PoS system, inexpensive, easy, low-cost, ...
Spread the knowledge around. Hopefully someone can take this idea and make it into a cool project that lots of people will use.