Information on QR codes.
Free Android Phone app: https://play.google.com/store/apps/details?id=de.gavitec.android
Free iPad app: http://itunes.apple.com/us/app/neoreader-qr-reader-barcode/id284973754?mt=8&uo=4&at=10l6SU
Free iPhone app: http://itunes.apple.com/us/app/neoreader-qr-reader-barcode/id284973754?mt=8&uo=4&at=10l6SU