I have encountered a site which I am beginning to love called Postcrossing where you can send and receive postcards all around the world.
So far I've sent postcards to Finland, Germany, Taiwan, the Netherlands and even the USA. I've only received so far from California, so I guess there are more Americans registered than other users, but I look forward to the day I get my first international postcard.
You too can join in on the fun by clicking on the link and setting up your account. You can send out 5 postcards at any one time once you are new, but later once you've sent/received more, then that number goes up.
If you'd like to turn your postcardee into a penpal you simply add your address to the postcard and make the request.