I would love to receive standard-size (and preferably single-view) postcards featuring traditional costumes. Donkey cards, bird cards, map cards, beaches !!!!, classical paintings are welcome, too. However, I'll be happy to receive any card you choose to send.
For Chinese postcrossers: a Peking Opera postcard would make my day.
For US postcrossers: a postcard of the bird of your state will make me happy.
From Germany, I'd love to receive a postcard of Neuschwanstein (although I have already received some, more are welcome :))
Also, if you have cards from tiny countries like Liechtenstein, Andorra, San Marino, Monaco, etc. -- I would be grateful for one, too, even if you do not live there.