Send Mail Get Mail - A postcard-sending website.
Fizzer - Send a personalised postcard with your photos. Holiday cards, thanks, greetings, invitations, birthdays and announcements.
The Simple Postcard - Text a photo to mail it as a postcard
MyPostcard - Send real photo postcards and greeting cards - worldwide, from any place to anywhere.
NanaGram - Text your photos and we'll mail 4x6 prints to your Nana.
Postsnap - Postsnap's iPhone app is the best, free postcard creator. Make & send real printed postcards, greeting cards, invitations and announcement cards using your own photos.