QR Codes:

A QR code (abbreviated from Quick Response code) is a type of matrix barcode (or two-dimensional code) first designed for the automotive industry. More recently, the system has become popular outside of the industry due to its fast readability and large storage capacity compared to traditional UPC barcodes. The code consists of black modules arranged in a square pattern on a white background. The information encoded can be made up of four standardized kinds (“modes”) of data (numeric, alphanumeric, byte/binary, Kanji), or by supported extensions virtually any kind of data. (source: wikipedia [code for mobile QR code image scanners to the right])

QR codes generators:

URL:

Google Charts: http://chart.apis.google.com/chart?cht=qr&chs=200×200&chld=l&chl=http%3A%2F%2Fen.qrwp.org%2FQr_code

SPARQCode:

Phone Numbers: