Gwyneth Jones uses QR codes for sharing information about books:

but take it a step further and with an idea stemming from a conversation with Tony Richards:

• bundle your students' creative responses to each text by creating a fur.ly link shortener which can link multiple URLs,
• then create a QR code and print and paste inside the relevant library book
• students with access to handheld devices with a camera or a computer with a webcam can take a photo or scan the QR code (I find Google goggles to be a great QR code reader) and be sent straight to the students' creative responses.
• As we know, student referrals are the best way to advertise a book. and what a way to sell a book! 

Have a look at this example for Lili Wilkinson's A Pocketful of Eyes: