How much is a Facebook like worth? For Pepsi, it was the price you paid for a can with this vending machine that connected you to your Facebook profile either through your smartphone or the machine directly.
TBWA Belgium created The Like Machine which only required a profile if you wanted a free can of Pepsi.
Of course, this option is only really available if you have deep pockets like Pepsi, but as a way of getting people to drink your product without having to rely on promo girls or people handing out samples, it's definitely one of the better ones. Less intrusive, more personal and a way to remind them of the product long after they've tasted it. Not an original idea, but an effective one all the same.