Wall Street is now starting to believe that the last big thing could also turn out to be the next big thing, writes Richard Waters.

It all looks so Last Century. EBay, the internet flea-market, is once again worth as much as Sears, The Gap and Federated Department Stores combined.

Online travel service Expedia is worth more than the six biggest US airlines put together. And Amazon.com stock is trading at four times Barnes & Noble and Borders.

The internet's boom-time stock prices are back, as a handful of survivors has emerged from the wreckage. Only this time around, the web has become a very different place to do business.

Real sales and earnings, not eyeballs or click-through rates, are now the main yardsticks for stock prices - even if those measures have been stretched almost to the point of incredulity.

In some ways, things seem to have changed little since the bubble. Share prices are still based on a belief that the infant web will consume vast swathes of the retail, travel and media industries.

Take USA Interactive, the corporate vehicle of media entrepreneur Mr Barry Diller, who this week pulled off the latest in a string of web deals with an agreement to acquire financial services site LendingTree.

Through Expedia and Hotels.com, Mr Diller is already the world's biggest online travel agent. Yet he claims this is just the beginning: with less than 15 per cent of US travel sales - in Europe, only 1 per cent - conducted online, there is plenty of room to grow.

Some time over the next decade, Americans will be booking more than half of their personal travel online, industry forecasters say. The current level of share prices already treats much of this growth as a certainty.

EBay's shares have now touched a level they topped only during a dizzy two-week spell at the peak of the dotcom bubble.

Among other battered stocks to see an impressive, though lesser, rise are Yahoo!, which has climbed threefold from its low of last autumn, and Amazon.com, which is up fivefold since its nadir in 2001. Internet stocks are the only corner of the tech sector to have gone up over the past year, according to Merrill Lynch.

Three years on, the few remaining dotcoms have at least notched up a track record that makes the grand promises of the bubble seem a little less pie-in-the-sky.

EBay has lifted its revenues from around $200 million (€174 million) to $1.2 billion, while its profits have jumped from $10 million to $250 million.

Amazon, though yet to turn a full-year profit, has more than doubled revenues and is now edging into the black.

At 70-80 times expected earnings this year, the internet companies are still off the charts compared with traditional stocks - although at least they are being compared on the same scale.

But to keep growing at exponential rates the small band of internet survivors will have to master new skills.

Three that have bedevilled many traditional off-line companies in the past stand out.

One is acquisitions. The dotcoms have started to mop up smaller rivals in a bid to consolidate their foothold and extend their reach into new markets. Besides Mr Diller's acquisition spree, Yahoo! has bought internet search and online recruitment companies, while eBay bought the biggest online payments company.

A second new skill, as they move into new markets, involves cross-selling to existing customers. Part of Mr Diller's promise is that he can sell hotel rooms and sports tickets to people who come to Expedia to buy airline seats - something that sounds easy but which few broad-based consumer companies have managed.

Third, and perhaps most difficult , they must now conquer the world.

Though far from mature, the US internet market is slowing: the best chance to keep the exponential expansion going is by exporting America's dotcom successes.

"For Hotels.com and Expedia, the biggest growth drivers are overseas," says Peter Mr Mirsky, an analyst at Fahnestock.

EBay's international revenues are soaring, while Yahoo! plans to reproduce its US businesses in the largest overseas markets.

It may be that the rest of the world's consumers are not as ready as Americans to rush to the net. But Wall Street's "buy" signs are already signalling that the next generation of multinationals is ready to reach out to the world.