Hear the words "pervasive computing" and you think of the distant dreams of technocrats: a time in the future when everything from the fridge to the car is web-enabled, really is upon us.

Yet, away from these grandiose schemes, digital technologies really are making their way into high streets, museums, pubs and clubs. The introduction of devices such as i-plus points - internet terminals which sit in streets and provide access to local travel news, council websites, job information and send-only email - may provide clues as to how pervasive computing business models may develop.

The i-plus points are pro vided for local authorities by Cityspace so people can get information while they're out and about. Mark Meyohas, Cityspace's managing director explains why: "The more people get wired up, the more they become reliant on the ability to access digital services."

This kind of quick, straightforward access to information is typical of the way people use the i-plus points, which can be found in several London boroughs, Cardiff, Bristol and other city centres. Most users spend just four minutes on the device, time enough to send an email saying they're running late.

But while the attraction of free digital services for consumers might be obvious, what does Cityspace get out of the deal? According to Meyohas, the company has two revenue streams. One is from advertisers who pay to go on the system, but most of Cityspace's revenue comes from local councils.

Cityspace offers councils the option of paying for digital infrastructure via either a straight fee or a barter system. Instead of paying £10,000 for each i-plus point, councils can opt to give Cityspace's sister company Adshel the right to erect advertising billboards. In turn, Adshel then pays a fee to Cityspace (a similar system has been used with bus shelters for years).

In Bristol, this approach dovetailed with the council's wish to create a "legible city". Bristol is, in the words of Alastair Brook, team manager for urban design in the city, "very multi-centred". Brook says that, as part of a city-wide regeneration effort, the i-plus points are used in conjunction with signs and maps to help people find their way around. In addition, councils can use the i-plus points to get information out to residents who don't have access to a PC.

In the near future, it's this kind of integrated advertising and media-driven model that is likely to become commonplace. Already trains to and from Heathrow show a BBC news bulletin, while bars in London show digital ads on screens above the urinals.

According to Matt Travers, European creative director of the applied concepts laboratory at e-business solutions provider Agency.com, this approach works because "marketing is a value exchange that happens between business and consumer without any actual real transaction occurring."

But Travers, who helped create a text messaging pub quiz game for Interbrew, warns that the roll-out of more ambitious applications and services will depend on third generation mobile phones, and a straightforward payment system. Unless pervasive computing devices and applications are easy and fast to use, why should anybody bother with them?

E-business solutions provider Crimsonwing has been creating catalogues that enable engineers working in the field to order a limited number of crucial parts on a personal digital assistant, rather than wasting time wading through all the products available on a complex electronic B2B exchange.

According to chairman Mike Winch, previously IT director at Safeway, the key lies in creating applications that are genuinely useful and delivered via devices that are appropriate to their environment. "These devices by definition will be pervasive," he says. "We won't just have one PC, we'll have several pervasive devices - in the kitchen, in the car, on your person."

Hewlett-Packard's Bristol research laboratory gives a glimpse of such a future. There, a team has been developing Cooltown, an imaginary city where "people, places and things have web presence." In such a city, your car would be able to diagnose a problem when it breaks down and then contact the garage. "What we will see is a world wide web infrastructure that is much more adapted to service, to delivery of real-time information," says Cooltown project manager Simon Crouch.

For those companies that come up with applications and devices used on a day-to-day basis in such a future, the potential pay-off from pervasive computing is huge. The early evidence is coming to a city centre near you.

Web addresses:

Cityspace: www.cityspace.com

Agency.com: www.agency.com

Hewlett-Packard: http://welcome.hp.com/country/uk/eng/welcome.htm

Crimson Wing: www.crimsonwing.com