This little mockup almost speaks for itself:

Almost… but not quite. The story it represents is really remarkable. Nina Simon explains:

Haarlem Oost is a branch library in the Netherlands that wanted to encourage visitors to add tags […] to the books they read. […] To do this, the library didn’t create a complicated computer system or send people online. Instead, they installed more book drops and return shelves, labeled with different descriptors like “boring,” “great for kids,” “funny,” etc.

Is that great or what? Physical tagging! It feels like the informational equivalent of turning a dance floor into a piezoelectric power generator. But alas—the library has now abandoned the system. Why?

[…] people were using the system so seriously that it took them a lot of time per book to decide where to place it. That caused some logistic problems in the (small) building, especially as they have some peak times.

It’s clear to me that this is a totally beautiful, clever mechanism—it makes me want to use the too-snooty term of art “intervention”—that just needed a little extra engineering. There’s a great comment thread over at Nina’s blog that dives in even deeper.