QR codes explained

QR Codes seem to be everywhere these days, and each has a unique destination. Ellie gives you a look at some of the most popular QR code reading apps for your mobile device and where to find these elusive codes!

In The Netherlands QR codes are used for a game i discovered called Het DamSpel.
I'm planning to play it soon and write a review for this site.

Do you have good exampes of QR in public?