The USPS is now offering an interesting (and very clever) combination of “e-cards” and postal service. You can design a greeting card by hand (even uploading digital images to it), define your message, even include a gift card in it and define what sort of stamp to use, and the USPS will then snail-mail the result to the recipient of your choice.
I will have to try this some time to see what it’s like (and what it costs), but it’s a great way to combine the convenience of e-cards with the “tangibility” of real greeting cards. Nice.