Jonathan Stark has a Starbucks card, and he wants YOU to use it. Really. Go ahead. There's no catch. Oh, except for this one. By DOWNLOADING Jonathan's Card to your smartphone and using it for free coffee, you're taking part in one heck of a caffeinated social experiment. He's inviting people to use the money on his card to buy coffee, then asking them to TWEET about the project. And if they want, they can put some money back on the card. He has a TWITTER ACCOUNT that updates the current amount on the card. Stark says it's a modern-day take on the "take a penny, leave a penny". The idea is that the generosity of strangers will offset all those free lattes. But will it work???