Despite some news reports proclaiming NFC credit cards can be read by passing strangers, in my experience the card has to be in close contact with the back of the phone to get a good read.
Out of paranoia, this app censors credit card info and the content of "track 2 equivalent data" as I would hate to release something that could be used for evil.
This app has only been tested on UK cards, with a Galaxy Nexus so may not work on other credit cards. The app does not save or transmit any of the read data, but you use it at your own risk.
This mobile application demonstrates the open TCP communications that is available with the Siemens S7-1200 PLCs. This application turns your mobile device into a control panel for the PLC code in the contoller. The PLC project can be downloaded from smithbackyard.com. Together, the PLC code and this application can control your home sprinkler and accent lighting. The PLC code is available for free as well (MIT license).