If you like to write by hand, and some of that writing involves the postal service, you may be interested in an excellent (and totally free service) called Postcrossing. Once you sign up for the service, you can begin by sending 5 postcards to individuals around the world, all of whom are chosen randomly for you by the website. Each postcard has a unique number that you write on it (provided by Postcrossing) that allows the postcard to be tracked when it reaches the recipient (or if it goes astray and never gets to its destination). With each postcard that arrives safely, your name is placed in the queue to receive a postcard from someone else somewhere in the world. So if you keep up with the service, you can be constantly sending and receiving postcards. While you can't demand certain kinds of postcards from others, you can write in your profile about the kinds of postcards you like, to guide the people sending you postcards. While I am not a very faithful postcard sender, it is a fun and wonderful service. As you send more postcards, the number you can have out at any one time gradually grows.
There are two drawbacks to it, however, neither of which are Postcrossing's fault. One is the postcards themselves. If you don't live in a big city or a tourist destination (which I do not), it can be hard to get and keep enough postcards to actually send them out. I have just ordered some postcard books from Dover Publications in hopes that that will tide me over until I do some more traveling. I have also ordered some postcards from Zazzle that have pictures of things and places from my state. We'll see if all that will be enough!
The other drawback is postage. If I get a U.S. recipient, it's no big deal, because postcard rate to U.S. addresses is 29 cents. A bargain! But the postal rate for a postcard being sent to an international address is a whopping 98 cents. So if your first five recipients are all international, you've spent $5 even before you factor in the cost of the postcards, which are not exactly cheap. This doesn't seem like a lot in the short term, but it does add up over time. Still, I suppose it's cheaper entertainment than lots of other things. And that postcard in the mailbox from a total stranger does give one a little lift at the end of a long workday!