Last month we reported on a watch that allowed you to pay at the till without having to get your credit card out, now Citibank in America has launched a keyring that does the same thing.

The MasterCard PayPass is a little RFID token that you wave in front of a reader and the charges appear on your credit card bill.

Standing for Radio Frequency Identification (RFID) is an automatic identification method, relying on storing and remotely retrieving data using devices called RFID tags or transponders.

Passive tags require no internal power source, whereas active tags require a power source.

PayPass uses this technology to allow users to make quick and easy transactions usually under $25 by simply waving the device, this time a keyring in front of a reciever. Customers can make transactions over $25 however most retailers require a signature for larger sums.

The system is designed for greater security than conventional cards, because your PayPass never leaves your hand.

Whether PayPass will catch on the UK, now that the Chip and Pin system is in place, remains to be seen.

According to one report, Royal Bank of Scotland plans to roll out the technology in the UK later in the year, giving the phrase "time is money" even more credence.