Pondering the fate of the QR code, @seanx offers four ideas on where they might make sense

Idea one: Scavenger hunt
My first idea is a scavenger hunt using QR codes placed around a city. Each clue leads to the next clue but requires the clue before it to make sense, and each clue is placed in an ad for your brand. You initially blast a single QR Code to people via a print ad or email. The program can be scaled to cities across the U.S. and the world, enabling you to have a global scavenger hunt. It is not important what the "prize" is at the end: That could be handled a variety of ways. It is important to use technology in ways that engage people and help foster interest and buzz outside of the program itself.

Idea two: Bar coasters dares
QR codes on bar drink coasters with dares for the person to do, such as "Go up to a woman and tell her this... [a phrase in a different language]" The trick is that most of the time neither party knows what is being said. That spurs an inquiry which usually results in some type of social interaction. Engaging with consumers and encouraging the social aspect helps solidify your brand in a positive reinforcing way. The phrases, pickup lines, dares, whatever you want to use are just ways to encourage social interaction associated with your brand. And social interaction associated with your brand is what causes positive reinforcing moments of memory that greatly facilitate positive brand recall.

Idea three: Print or online banner adjunct promotion
If you include a QR code in a print ad, instead of having it just go to your website, create a promotion where some of the thousands of QR codes printed on those ads win something. What you are really trying to do is have people engage with the ad you are already paying for. You do not actually believe that when you have an ad printed on a newspaper or a magazine that most people actually notice it, do you? Use creative ways to encourage engagement with the mediums you are already spending money on. You could do the exact same promotion online with banner ads. If you really want people to notice your online banner ads, then give them a reason to not only look for them but engage with them. Do not have the print ad or the banner be about the promotion: Have it communicate what it normally would. The QR code on it is a technique to help facilitate the message you want communicated in the first place. It's a way to get people to pay attention to you!

Idea four: Triggering curiosity sells
The "unknown" sells, as does the creative use of our own "imagination of possibilities." One of the greatest advantages of QR codes is that you cannot read them without technology. Use that. Develop a strategy for implementing QR codes on your ads that go to a webpage with something provocative on it. Or just have it say something that the ad could not, like a tagline that is way over the top, or some hidden message for those willing to engage with it. People like to feel as if they are part of an "in" group. They will go to great lengths to try and differentiate themselves. Your ad can provide the ego with a nice little hit of juice.