those square "bar codes"

Bar codes no longer look like bars, they have taken all kinds of shapes.
Some of them can contain either text, email, contact info, phone number, or even a google maps link.
Using http://www.qrstuff.com/index.html   you can create your own "QR" code.

For example the above contains a name, email, URL, and phone number.
How to read it ?  Simplest is to use a smarphone app like Google Goggles, which uses the built in camera on the smartphone, takes a picture of the code, and interprets the code (works on bar codes too, and many other things).    Otherwise look for "QR reader" and you will find applications as noted on http://techie-buzz.com/softwares/read-qr-codes-on-pc.html, or http://www.dansl.net/blog/?p=256 .  <-disclaimer: I have not tried these apps.

(Note:  the geolocation is not for me, it is trying to find where you are...)