Quick Response (QR) Codes are slowly catching on in print media, from magazines and newspapers to product labels and billboards (a dangerous variation, in my opinion). Many people still don't know what they do, and the majority of marketers aren't yet using them, but they are a handy way of letting you scan a link with your smartphone taking you to the Code owner's Website or landing page.
There are numerous free online generators
to create QR Codes for any URL.
But they are not the only game in town. Apart from standard 2D bar codes that have been around for decades, there are other kinds of 2D and 3D bar codes that encapsulate much more data than the standard 2D bar code, and in a more compact space.
There's the colorful Micorsoft Tag:
The MaxiCode tag:
The Data Matrix
And image recognition tags like the Blippar and some specialized Custom Tags using image backgrounds (produced by Microsoft).
In short, even before QR Codes have become widely adopted, there are numerous competitors. And with image codes, the sky's the limit on how we will be interacting with Weblinks and smartphones in the years to come.