Catherine Casey shared this picture (click to enlarge) of a medicine sold in Nigeria, where counterfeit drugs are a huge issue. Each packet comes with a scratch-off number. Use your cell phone and SMS the number to the company, and the company will text back whether the packet is legit. I'm sure clever counterfeiters will try to game the system, but it's not that hard to make it work.
It's easy to imagine ways that this could be used to increase after-sale connection (offers, insight, instructions, coupons) for all sorts of items, particularly in parts of the world where SMS is cheap and ubiquitous.