I’ve seen QR codes creatively used before, but these (pictured below) seem to be more effective.
When you’re advertising a mobile app with a QR code, you’re much more likely to be effective, since your 100% of your target audience has a device that can read them.
When you’re using a QR code on a billboard advertising Coke, for instance (more xamples), you’re essentially asking those passing by to stop what they’re doing and watch an advertisement. The only incentive is extinguishing curiosity. This is effective for the short-term, but is a lousy long term strategy.
These ads, however, creatively advertise the iPhone App, and by scanning the QR code, can be instantly downloaded.