Sure you can comment, add your two cents, and post corrections in today's boisterous social media landscape. And it's great.

But "leaving messages on the wall" is hardly a new phenomenon.

Yet another thing I like about the pedestrian life is the posters (and more specifically, the heavy metal posters—what a rarefied and bizarre genre for something that's so commonplace). 

And the graffiti.

And my ability to leave comments and join the conversation.