Imagine if you could open your front door using your mobile phone. It might sound like a futuristic idea but Apple has patented a system which allows the iPhone to communicate with external devices such as locks. Behind this magical door-opening concept is RFID technology, which currently allows you to wave an Oyster card over a reader to get into a station, for example.
Instead of waiting for this magical technology to appear on the next iPhone though, a research assistant at CASA/University College London has managed to build his own RFID iPhone accessory (video below). Benjamin Blundell's iPhone RFID solution is explained in great depth on his blog. Blundell's solution reads RFID data but can't write it yet, which means it can't be used to open doors at the moment but it does demo how the iPhone could interact with external objects.
It's worth noting that last April a team of researchers at the Oslo School of Architecture & Design (OSAD) demoed an iPhone RFID reader and later that year a company called Wireless Dynamics announced an RFID iPhone and iPod Touch accessory called the iCarte. The OSAD demo didn't include instructions on how to build a reader and we can't seem to find anywhere in the UK that sells the iCarte. So if you're desperate to get involved in some iPhone RFID action then Blundell's instructions should be very helpful.