Looking for a simple way to teach your kids about geography, and stamps, and good-old-fashioned letter-writing? Look no further than PostCrossings, a clever little site where you can sign up to receive an actual paper postcard in the mail from some random location anywhere in the world, all for the price of sending one out yourself. It’s like old-skool pen pals for the digital age. It’s a popular little site, too: more than 2 million postcards sent so far, and around 380 postcards mailed every hour.

This type of site has always fascinated me. Maybe it’s the intersection of web connections and real-life interactions. I admit to trying my hand at BookCrossing back in the day, and I’ve tracked a few $5 bills on Where’s Willy. (American readers can play along at Where’s George.)

Photochaining is the latest iteration of this idea, found via CBC’s radio show and podcast Spark:

What do you get when you combine cheap digital memory cards, photography enthusiasts, and online voyeurism? Photochaining.

Photochaining is a new concept from Belgian blogger Renaud Dehareng, who describes it as “the art of leaving memory cards in public places to be picked up and used by others, who then do likewise.” The photos are then uploaded to the Photochaining blog for all to see. And it seems Canadians are getting in on the action. Two of the submissions so far are from Canucks: one from Toronto, and one from Kelowna.

What’s the appeal of these sites? Pure whimsey, I’d say. They appeal to the same sort of folks who are using their GPS systems to hunt for tiny treasures while geo-caching. Surprise, discovery, randomness — we could all use a little more of these in our lives, I think!