If a person has a "paper wallet" how can they transfer BTC to another person. I'm sure there are several ways, but what are they?
I believe mycelium for Android will do what you want. It has an option when you press menu for 'Cold Storage' which asks for the QR code of the private key.
It also allows you to export the private key which happens to be in QR format and easily fits in your pocket.
However, I've never used it and could be wrong.
Use blockchain.info as a last resort, or if you have an iPhone.
