Remember that firm ShotCode, that makes it possible to buy stuff -- concert tickets, soft drinks, tennis shoes, etc. -- directly through your phone when you take a picture of the target-shaped bar code?
Here's a new, similar application that's getting tons of press today: SnapTell. This program rewards customers (who photograph ads and text them to a special phone number) by sending them free ringtones, videos, games, etc. No bar code required.
Both programs greatly enhance ROI for advertisers, since the ads, and the contact phone number, will allow them to track exactly which ads the customer are seeing and responding to. They can be anywhere -- print, outdoor, guerrilla, etc. Of course, the advertisers also get the benefit of all the database info they can compile based on user-supplied information.
You can check out SnapTell ads in the current (and future?) issues of Rolling Stone and Men's Health magazines.