But so far, the web’s claim to the market is nominal. Says Forrester Research analyst Matthew Sanders: "We’re just cracking the surface." Count among the trailblazers BuildPoint.com, which specialises in a bid management and procurement marketplace and which has generated more than $1 billion worth of subcontracts in less than three months. Players such as Bidcom, Bricsnet.com, and Cephren have collaboration tools that track project specs, cutting costs and reducing errors in work flow. Other online tools in the works: blueprint editors, web-cams "that show still-shots of the construction site " and automatic e-mail notices when a project has been changed or updated. The multifold benefits include vastly greater efficiency, reduced procurement costs and less communication runaround. If the industry takes advantage of shipping marketplaces such as GoCargo.com, which auctions off excess space on barges, the savings could mount.

Utilities sector
Total market: $357 billion; Net share: $5.2 billion; Net share in 2004: $108 billion of a $385 billion market.
Moreso than the Net itself, in-progress deregulation of the utilities industry is driving changes here. Consumers in 21 states can now choose their power and gas suppliers, and nationwide deregulation should be complete by 2008. Meanwhile, the Net has merely given utility companies a user-friendly makeover, and generated a few online middlemen with moderate effect. Deregulation and the Internet have forced utilities to become more customer-friendly through online services. Led by Con Edison and Boston Edison, the industry has been the fastest adopter of online bill presentment and payment, which saves $1.15 per bill " that’s $23 million for the industry in 1999 and a whole lot of trees.

Real-time billing and metering online is coming soon. Problem is customers must adopt the services in order for them to matter. Companies such as Con Edison send bills online and through snail mail unless customers request otherwise. But over the next two years billing will migrate online, predicts Datamonitor’s Alison C. Hills.

Here’s where the action is: Altra is the online B2B energy exchange where utilities buy and sell oil, natural gas and energy. Other companies have emerged as online power middlemen who buy wholesale from power producers and then mark it up for online sales. Utility.com promises cheaper rates (though the difference is minimal to most consumers) and GreenMountain.com sells only wind, hydroelectric, solar and geothermal power. Essential.com bundles energy with phone and Internet access. Feasible...if customers want brand-name power.

Manufacturing sector
Total market: $4.2 trillion; Net share: $134.4 billion; Net share in 2003: $1.7 trillion of a $4.8 trillion market.
The manufacturing industry feels the Net’s impact along every link in the supply chain " from web-enabled design software to online order-tracking systems " and now customers can have a hands-on role in the process. Here is the latest scenario: an online shopper configures a computer to fit her needs; the order is sent electronically to a contract manufacturer that builds to order; second-tier suppliers get a heads-up on which parts to send the manufacturer; the customer tracks the status of her order as it is built; and the whole process is data-mined to forecast future supply and demand.

Soon companies will specialise in a stage of the business process and link to one another seamlessly through the web. According to AMR Research analyst Bill Swanton, "To the end user it looks like one company." Good news for contract manufacturers, which sell otherwise idle machine-time to companies such as Cisco Systems and 3Com, which have limited in-house manufacturing capacity. This isn’t easy. Sales force automation software made by Selectica, Firepond and others must jibe with the back-end systems of contract manufacturers such as Flextronics, which in turn must jibe with supply chain management systems by i2 Technologies, SAP, Oracle, and so on down the line. It’s a monumental undertaking.

The finance sector
Total market: $1.9 trillion; Net share: $103 billion; Net share in 2003: $435 billion.
The Internet is the ultimate small-investor power tool " it provides access to real-time securities information, ground-floor IPO shares, after-hours trading on electronic communications networks, and index and futures trading. Since E*Trade (founded in 1982 as an institutional trading service) opened its online doors to consumer trading in 1992 through America Online and CompuServe, the Net has become an enormous empowering device for individual traders.

Consider online transactions.
The cost of each trade has been greatly reduced by automated online trading services. Concurrently, the number of online trades has skyrocketed. The banking industry is about to undergo a similar transformation. Wells Fargo was the first large US bank to offer online banking in 1995 and other big banks followed.

The next major development, according to Jupiter Communications analyst Rob Sterling, is financial engines that help individuals make long-term personalised planning decisions through web-based applications. Merrill Lynch and American Century Services are in the lead.

Looking beyond that, Sterling predicts systems intelligent enough to allow investors to delegate the responsibility for managing their financial portfolios to other parties over the Internet. By setting up rules " at what price point to sell a plummeting stock, for example " investors could hand off the management of a 401(k). But that takes trust, which is another development entirely.

Insurance industry
Total market: $500 billion; Net share: $450 million; Net share in 2003: $4.1 billion.
Don’t hold your breath here: Ninety-nine per cent of all business in the insurance industry is still done the old-fashioned way " a way entangled in more paperwork, middlemen and fine print than any sector imaginable. Few companies sell policies online, though some offer claims assistance. Aside from a few quote-gathering tools, there are few new online business models.

On Quotesmith and Insweb, customers can get quotes from several providers with just one form. Cybersettle and clickNsettle.com, independent form-providers, enhance the speed and efficiency of the claims process by eliminating paperwork and phone tag between attorneys and carriers.

ECoverage and Esurance are online-only insurance providers that promise cheaper premiums because they are unburdened by physical - world overheads and an army of salespeople earning commissions. Good luck. For most types of insurance, "loss cost" " the cost of paying out claims " comprises 70 to 75 per cent of the firm’s total costs. The costs are outweighed by the sheer masses of policyholders who, in probability, won’t need to file a claim. But if these dot-coms reach the critical mass, their opportunity lies in the 8 to 15 percent of expenses traditionally incurred through agent and distribution costs " something dot-coms won’t have to shoulder.

The news sector
Total market: $54 billion; Net share: data not available; Total market 2003: $58 billion.
Read all about it: To say the Net has changed news is selling short its impact by a long shot. Once embodied by ink-smeared newsprint, the industry is a whole new story: personalised, customised, interactive and on-demand news zapped straight to a desktop or a wireless PDA. Printing and distribution costs are gone. New media can scoop print in breaking news. And most of it is free.

But there are drawbacks. Ad-revenue business models that work in print often falter online due to online advertising’s sketchy reputation. Most online papers cannibalise the ad revenue of their offline counterparts.

A perfect medium for classifieds, the Net sucks away the classified ads that account for up to 40 per cent of newspapers’ revenue. The Wall Street Journal Online is the only major newspaper to have pulled off the subscription-based model online. Ironically, new media is expanding into old media. Yahoo! publishes a magazine, while Slate.com launched Slate TV.

What’s in store for the future of news? Chris Feola of Belo Interactive predicts "digital papers" that are high-resolution, wireless, interactive, and roll up like a good paper. It might solve one huge bug in online news: You can’t take the web to the toilet.

Healthcare industry
Total market: $1.4 trillion; Net share: $6 billion; Net share in 2003: $178 billion of a $1.9 market.
In the behemoth healthcare industry lies the Net’s biggest opportunity to revolutionise a sector that affects almost everyone. The $1.4 trillion national market accounts for roughly 14 per cent of the USA’s GDP, which comes to $5,198 per person per year. But a mere fraction of a per cent of this market is online.

The Internet touches all subsectors: patients, providers and pharmaceutical companies. Educational sites such as drkoop.com create better-informed patients. Healtheon/WebMD and Pointshare streamline the flow of information - bills, lab results, claims and eligibility forms - between healthcare-providers and insurance companies.

By some estimates, up to 25 per cent of healthcare spending falls into these categories, and eliminating inefficiencies of paperwork and human error could save a company a significant chunk, says Philip Ma of McKinsey & Co.

The Net is also a supply-chain tool for pharmaceutical companies, which can purchase supplies and chemicals from a growing number of online marketplaces such as Chemdex (a division of Ventro) and Neoforma.com.

The dream " and nightmare " of the healthcare industry is standardised electronic medical records. Software makers such as HealthMagic and WellMed are trying to push this capability into the hands of consumers, whose pressure might drive otherwise technophobic doctors to get online.

Other tools could link to such records. Allscripts, MDeverywhere, ePhysician and Iscribe are writing software for handheld devices that could speed clinical processes such as writing prescriptions, ordering lab tests or checking insurance restrictions.