we have the Octopus card in Hong Kong which works for convenience stores, subway and other transportation fees, and some retailers like Starbucks or our local supermarkets. it can only be topped up to 500HKD($64.43USD) at any convenience store or subway station and is anonymous. it uses an RFID chip, so it doesn't need swiping, just place close to the machine will charge the card.
same goes for Japan's Suica card, which was only for Tokyo before but has just gone national.
having an electronic currency card is wonderful, instead of having to pocket so much change for those times u need to use the payphone or pay for a one time bus ticket or buy something from a vending machine. and it's not attached to my credit or debit card, so i can hand it to a relative or friend when they visit me in Hong Kong, or i can buy a Suica card in Japan and use it just for the duration of the trip without worrying about daily exchange rates.