ahhh wondered that myself, but dont you still have to use a credit card with an American billing address? Or did your American friend send you the gift certificate?
Actually, it was not even a friend that sent me the certificate.
I posted a request on this forum for someone (american) to send me a certificate and within 5 minutes this guy Laurent sent me one. I consider him now a friend now.
Already suggested to him to make business out of this, selling certificates to non-US users with a little extra commission.
I can assure you, that would be worth it, especially since the euro is rather expensive right now (I am paying only 0.88 instead of $ 0.99)