I stumbled across this very cool website the other day. It's kind of a postcard pen pal matching service. When you register, you can get up to 5 addresses of people to send postcards to and your address gets put in the pool. When the postcards you've sent out get received, you can get more addresses.
I have a box of postcards from my travels that seem to have been waiting for something like this. I'm sending out postcards to Germany, Finland, China, Australia and Estonia today. I can't wait to see what shows up in my mailbox!