RFID
This relatively inexpensive RFID reader was built with around $40 in off-the-shelf equipment and a few hundred lines of code. The device includes a small, cheap computer, an RFID chip reader, and some RFID chips. The hardware, part of a project called Arduino, allows nearly anyone the ability to make small gadgets for a hugely diverse set of purposes: automatically unlocking doors, tracking patients at adult care homes, moving furniture around, collecting audio for art installations, and more.
I constructed this particular device as proof of concept for a book tracking surface. The white cards (or a similar small chip) embedded in the bindings of specific books can be used to track the books when they pass scanners. The project would scale easily, meaning it would be (relatively) trivial for someone to build a program that tracked the movement of every book in their personal (or institutional) library: The hardware and software would be on the order of hundreds of dollars while the individual RFID chips cost pennies when purchased in bulk (so cheap that Wal-Mart is in the process of embedding them in consumer disposable products such as shampoo bottles).
Texts, in this world, gain identities: They move, they form alliances and make friends. More importantly, we gain the ablity to see how those texts move. What will it mean when we can show each other detailed maps of the migration of texts in a gifted scholar's workspace? When we can examine our own and others' maps to note useful patterns or disruptions?