Looking for something personal and fun to send someone?  Consider a postcup.  It’s a simple porcelain mug that comes with a special marker.  You write your message then bake the cup in a regular oven (no kiln needed) and then send it on its way, though I think it requires more than the $0.29 of a conventional postcard.  The message is permanent, but since it was only baked on in an oven (is there even a cone for that?) they suggest you wash it by hand and avoid abrasives.  I think it makes a really sweet message delivery system.

You can buy your own Postcup  from the really lovely site Bailey Doesn’t Bark.