In the spirit of "damn, I wish I had known about this before my last trip," I found a great little website that is essentially a 'free' book club. 'Free' in the sense that you 'release' a book of yours 'to the wild' unknown, in a cab, in a taxi, on a plane, in a hotel, etc. There are ways to track where it goes if the finder decides to play along and it sounds like a very interesting way to 'contact' people and also share the love of reading, too. And there are ways to help 'find' any 'released' books, too, so you can get something back in return. Interested book lovers should check out Bookcrossing's site. I so wish I would have known about this prior to my international trips, especially this last one to Australia. (As most people know, the Aussies are a barbie (BBQ) fanatic group and NC is known as a BBQ fanatic state...yet very few citizens of either place know the recipes and goodness of the other. Next trip, I promise...LOL.) And since we live in a society where even our current President admits he reads very few books (explains a lot in some ways, doesn't it?), we need to get all the 'free' and good books out there to the public at large. Stat. If we can't stop Dubya in the office now, we can at least help prevent future Dubyas from occurring.
This flows similar in vein to another very popular website I do know about, www.WheresGeorge.com. WheresGeorge allows US $1 dollar currency holders to stamp and then follow the $1 bills that come into their possession. (Canucks, don't despair: there's a version for your notes, too, and you can link to it from the same site mentioned above.) You can see where previously stamped $1 bills have been prior to arriving in your wallet, can enter your own homestead, and then follow it down the line as hopefully others do the same. I'm not sure if it's a simple, everyday demonstration about capitalism at work or something more frivolous along the lines of the popular comic game of "Where's Waldo?" (Although I suspect the latter, I'd think the former could hold true for some kids just learning about how our economy works.) I'm not sure if this is done in other countries...I only know of the US and Canada so far...but I can't imagine a scenario why not. In fact, as global a society the world is becoming, I would think that would be a great eco-political experiment for younger kids (providing other countries don't have a problem with their currency being defaced and/or recipients could read what was actually on the bills...Egyptian money, for example, is so heavily traded and so dirty, I don't think too many people would even notice any writing, let alone actually be able to read it).
Of course, if neither of these options work for you but you still want to have some 'physical' contact with unknown peoples, you can always sign up for one of those 'camera exchange' logs that tons of chat rooms and online boards have going at any time, either with a group or even by yourself. In that scenario, someone buys a disposable camera that has prepaid developing (with developing envelope), and additionally also buys a small notebook as log and an envelope to send everything to the next recipient. They then take 2-3 pictures, give a brief history in the log, then mail the camera and its final developing envelope to the next person on their exchange list. The next person takes 2-3 pictures, notes the information about them in the log, and mails the whole thing again to the next person on the list. This pattern continues until all the pictures are taken and the last person on the exchange returns the camera for film processing in the developing envelope (and online viewing, so all participants can view), and then also writes up the notes from the notebook as the final captions once the pictures are posted online. (Some groups eliminate the traveling notebook altogether and just wait til the camera is developed, and then each member responsible goes in and captions their own photos...further adding to the final surprise. Both ways work, but it depends on the familiarity of your group photographers involved a bit, too.) It's a bit more work for the first and last users, but it can be fun...especially if your group is diverse and international, or if you go into the project with everyone trying to 'do' a certain 'theme'. I've done this a few times now and have had a blast each time. Works great with kids, too, to do at birthday parties or excursions instead of mailing everywhere...although some kids do it well with their pen pals.