One of the best applications that I consistently see when it comes to QR Codes is when companies are promoting mobile applications.
Here is a recent one from Chase. They took out a print advertisement to promote their JOT app. Within the advertisement, a QR Code was included to make it much easier for people to access and download the app.
The initial scan directed people to a mobile website where they could learn a bit more about what the app does; then, with one click they could download the app.