Several years ago a friend of mine told me about PostCrossing.com. It's a website where people can send postcards to each other. It might sound lame, but it's really fun!
Here's how it works: Once you're a member (which is free and easy), you can click "Send A Postcard" and the site will email you a name and an address of someone else on the site, along with a special code to put on the postcard. So, you make or buy a postcard and send it off to them. When they get the card, they log in to PostCrossing and enter in the code on the card signaling that they received it. Once that code is entered, you, the sender, are next in line to have a card sent to you! As long as you send a card, you'll get a card!
The whole thing is simple and fun. I've received 9 cards from around the world. Germany, Belarus, Holland.... And some senders go above and beyond: I got a postcard in an envelope once, along with a sampling of some tea that they liked and photos of their town.
The community is so friendly and you can even reply to the senders to say thanks or to continue writing. It's a perfect pen-pal finder!
The only downside is that I never have stamps on hand (especially global stamps) so I don't send postcards as often as I'd like. It does make it a treat to be able to send one and wait for the mailbox to bring back a card for me, though.
So, if you're looking for a fun and relatively cheap hobby that takes hardly any effort at all, try PostCrossing! It will make you and your mailbox happy!