When I first stumbled across Valleygram tonight, I was really impressed with the ingenuity behind it. By drawing on both Foursquare and Instagram APIs, it’s able to deliver Instagram photos sorted first by state, then by town, and then by categories within that town (Arts, Food, Residence, etc) and finally by specific locations within each category. Within a few seconds, I was able to pull up a variety of Instagram photos shot at my father’s favorite downtown pub.

Developed by Jeff Hobbs (a friend of a friend; I discovered his site via Facebook) it feels precisely like the sort of thing the Internet was made to do—and I’m still really impressed by it—but one thing made me a little uneasy about it: I didn’t know anyone in those pictures, and I’d guess they had no idea how easy it was for me to see them.

It’s an issue that has come up in similar ways before, most notably with the Girls Around Me app, which used the Foursquare API and publicly viewable Facebook information to give users a map of (and information about) nearby women. In that case, Foursquare pulled the app’s privileges after some bad press.

I don’t think Valleygram is doing anything explicitly harmful, but it does make it amazingly easy to look in on people’s lives, with each photo then linked to an Instagram account. It’s an important reminder about privacy in the Internet age; despite hearing complaints about Facebook’s privacy policies just about every other day, many of us still don’t give much thought to our own accounts. After seeing some of what gets pulled into the site—besides the usual drunken documentaries, there are also personal photos taken inside private residences, college dorms, and other semi-private areas—one hopes that at least a few people will be spurred to rethink their settings.