Encountered this awesome social media experiment via the Consumerist.
Jonathan Stark lets you download an image of his Starbucks card to buy a coffee or reload money to help others buy coffee. Pretty innovative. Read the info page here and visit Jonathan’s site for the actual image of the card to download to your phone and use.
UPDATE: Starbucks had to shut down the card due to terms of service violation. I would guess that the people taking money off the card for personal use was getting out of hand.