Adland's latest mad ideas: Wee-powered festival floats and magazines that charge your phone

Agencies all over the world are limited only by their imaginations as new technologies promise to bring marketing to life, says Simon Usborne.

It has become almost clichéd to say new technology is "like something out of Minority Report" (see also: "a bit 1984"), but what about this: software just released by a New York company turns any webcam into a human-sensing eye capable of adapting a digital billboard according to your gender and age within 100 milliseconds – before you've even noticed it's there.

The system, called Cara and developed by IMRSV (add your own vowels), can also tell how long you spend standing in front of the hypothetical M&S ad for a bikini/suit/slip-on shoes. And it knows how far away you are from it and how many fractions of seconds you spend looking directly at it. If nobody's interested, change the ad – now.

OK, it's not quite as spooky as Minority Report, in which Tom Cruise's character is bombarded by retina-scanning billboards in a futuristic shopping mall ("John Anderton, you could use a Guinness right about now"), but it's undoubtedly among the most startling innovations in a booming market for interactive or personalised advertising.

Agencies all over the world are limited only by their imaginations as new technologies promise to bring marketing to life, collecting new levels of press attention for products or campaigns and, increasingly, valuable data about consumers. Developments such as Cara are making it possible to use targeted ads in the real world in a way that has only been possible online.

Skip from Manhattan, where Cara is already being used inside a Reebok store to sense how long shoppers linger, to Wigan. Fabula, a London agency, was asked by William Hill this year to create "idents" for ITV's coverage of the FA Cup, which the betting firm sponsored. Rather than create ad-break bookends that served as cues for a tea break, Fabula's creative director, Yan Elliott, suggested an interactive alternative. For the final, which Wigan won, the agency took the FA Cup itself and hid it, Where's Wally-like, in locations in the city, challenging viewers to spot it. Those who followed the link on screen were given the chance to win free bets if they mentioned William Hill – and the cup's correct location – on Facebook or Twitter.

"Last year they used normal, quite static idents," Elliot says. "But they had no real impact they could measure. The new idents were engaging. People played the game, and commented.

"As we strive to get into people's consciousness and fight against other brands for headspace, it's becoming more and more important to reward and immerse the consumer."

Now to Rio, where a Brazilian agency, JWT, took a problem – public urination during the city's Carnival – and turned it into an opportunity to promote its client, Afroreggae, a social enterprise. It placed special banks of urinals equipped with hydro-electric generators to charge the batteries used to power the speakers on Afroreggae's float. Turning pee into music brought more attention via news reports than a whole city of billboards could.

Marketing gimmickry was used to similar effect last month in Spain to promote Afar, the country's answer to ChildLine. This time the charity's agency used an old technology called lenticular printing to create an advert that displayed alternate messages to small people – children – and adults. The ad was reported globally, including in this newspaper.

But new, hi-tech opportunities present a risk for the over-reaching creative of crossing the line between reward and manipulation. Elliott offers examples he believes fall on either side of that line.

Back in Brazil, Nivea commissioned ads in the shape of A4-sized solar-powered phone chargers with slim USB ports to be placed inside copies of the magazine, Veja Rio. An ad for sun cream that charges your phone on the beach in such a way that you'll talk about it – and need more sun cream. Genius.

Conversely, a Belgian company created Pepsi vending machines that accept Facebook "likes" rather than coins, planting them outside gigs as an interactive alternative to aimless freebie handouts. The machines, equipped with touch screens, required consumers to log into Facebook on their phones, and "like" Pepsi. If the phone's GPS location revealed proximity to the machine, out popped a can. You get a drink; Pepsi gets data about people who like it – or people who like freebies, at least. But, Elliott says, "There's a risk that the more cynical audience would realise a 'like' is not something to be thrown away and that they are just supplying data. Something like this could backfire".

Concerns about privacy and data are starker still in the case of adverts that use camera-sensor technology. IMRSV is quick to point out that Cara doesn't know who you are, or record your image, but only compares it with templates to determine what kind of person you are. "It can tell if you are a child, young adult or senior," Jason Sosa, the company's founder and CEO, says from New York. "It just gives us a general idea of groups walking past."

Other companies are getting closer to the Minority Report scenario, scanning not your eyeball to identify you, as in the case of Tom Cruise, but the phone in your pocket. The technology already exists for the chips in smartphones to gather information about your interests by monitoring who you call, the apps you use and the places you go. Walk past a cinema and receive an ad for a film that you might like. Ditto a billboard, bar, restaurant or shop.

Whether they are interactive, personalised or both, adverts are changing as fast as we'll let them. But for Elliott, we risk losing something else, if not privacy. "I can't help feeling a little sad," he says. "Maybe I'm odd but I quite like seeing ads aimed at other people. It's good for us to see what other people are interested in – life would be dull if everything is aimed at us."