Shanghai Public Transportation Card is very useful if you plan on staying in Shanghai for more than a week because you can use it when you get on the public buses, subway, taxis etc... You don't have to worry if you have exact change, how much is the fare etc...
They can be purchases and recharged at many local Metro Stations. They are contactless, you just need to put them close to the reader, there is no need to swipe it...
http://en.wikipedia.org/wiki/Shanghai_P ... ation_Card
Offical web site:
Here is how the card looks like:
http://i268.photobucket.com/albums/jj12 ... p_card.jpg