These are very nice, and include animation and sound. Musical Cardshop at Music City cards for a variety of occasions with MIDI music files you can attach. O to Go Ecards Oprah's favourite quotes with the sound of Oprah reading them herself attached. Sent as attachments. Net postcards that allow you to attach live radio station broadcasts from around the world.
Card images are of travel destinations and scenery.
Attach the song's midi. New cards added daily. A wide variety of sentiments. Wotch Mini-Cards this site sends cool interactive attachments that looks like real cards opening. Wynne's Post Office sends self-executing multimedia cards for anniversaries, birthdays, congratulations, and thank yous.