[ Thanks to linuxaria for this link.
“Probably you have already saw these small black and white image
in some sites or while walking around your city, or if you have a
smartphone probably you have already used them; they are QR
“This GPL software is available in Debian, Ubuntu and Fedora
repository, so just use your package manager to install it,for me
this means aptitude install qrencode (ubuntu 10.10).”