Modern mobile phones can do all kinds of things - including adding to the unemployment queues. When you install an app you're not just getting something that will make your life easier; you're contributing to the ultimate destruction of entire industries. Well, unless you're installing iFart, anyway.
There were two excellent examples this week. First, the car price guide Parker's launched a rather nifty iPhone app. Then, Nokia bragged about its Point and Find software, which can scan barcodes and automatically find the item on a price checking website. They're very different applications, but they could both have very serious implications.
Many industries depend on knowing more than you do. Car dealers know exactly how much your car is worth, and exactly how much the car they're trying to flog you is worth. You don't, and their job is to take advantage of that by paying below the odds for your car while getting you to pay over the odds for the new car.
Apps such as Parker's make that much more difficult: "A 2001 Saab 9-5 in average condition with 80,000 miles on the clock, you say? With metallic paint but not the AS2 stereo upgrade? My good man, with that price you're surely having a laugh!"
The more information you have, the less profit the dealer can make from you. The better informed the customers, the smaller the profit; the smaller the profit, the more cars the dealer needs to sell just to break even.
It's the same with other forms of retail. If you can scan the barcode on a flat-screen TV, a fridge, a Fimbles DVD or anything else you're thinking of buying, you can instantly discover where there's a better deal. It could be the shop next door, or a website. That's seriously bad news for high street shops, because the internet will undercut them almost every time.
It's not just shops, though. Estate agents should fear an app that enables you to point at a building, see whether the neighbours have planning applications or ASBOs, and discover the average selling price for every other house in the street - as well as showing other, nicer houses on the market.
Restaurateurs and hoteliers should worry about the apps that will show user reviews and scare off potential customers if their food or the beds aren't any good.
The only reason this hasn't happened already is that our net connections are at home, not in the high street, but of course smartphones are changing that.
The combination of cameraphones, apps and Augmented Reality is enormously exciting - unless you're a car dealer, or a shop owner, or a restaurateur, or a hotelier, or… well, pretty much any retail business.
Wholesale destruction of previously invulnerable businesses? There's an app for that.
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Writer, broadcaster, musician and kitchen gadget obsessive Carrie Marshall (Twitter) has been writing about tech since 1998, contributing sage advice and odd opinions to all kinds of magazines and websites as well as writing more than a dozen books. Her memoir, Carrie Kills A Man, is on sale now. She is the singer in Glaswegian rock band HAVR.