QRnote is a [free] web service where you can create your own mobile web site connected with QR code, which you can place anywhere - printed in real world, or saved on your website. Your QRnote could contain any content such as text, images, contact (vCard), event (vCalendar), or embedded discussion. The final QRnote is optimized for mobile devices
There is a lot of potential of using QR codes in the classroom and services like these make it easier to publish your content as a QR code, either on the web or in printed form. To learn more about how to use QR codes in the classroom, check my recent post on the topic.