Fewer runs to the post office

One of the things I do on my morning runs is drop my mail, usually birthday cards, etc. at the post office. I've started paying my bills online with my checking account so I don't mail bills much anymore, but I still mail greeting cards. Well, I see in the New York Times that there is a new web site introduced by American Greetings that allows you to send postcards to someone who has an MSN account or MySpace page. I already send e-cards, but this would make it even easier to send stuff to my friends and relatives that have these accounts. But what about all the others? The article said that 5 times more paper cards than e-greetings are sent, but American Greetings sold more than 10% fewer cards this year than last. Now, how do you tuck the money into the electronic card?