The internet bubble might have burst on both sides of the Atlantic. In the US, the Nasdaq, where many technology companies are listed, has slumped 40% this year, while e-retailers on this side of the Atlantic, including Boo.com and the most recent casualty, CD retailer Boxman, have gone to the wall. You could be forgiven for thinking that the notion of e-tycoons is as unrealistic as the hope of dot.com profits.

Not so. The internet has made millions for some, like newbie millionaires Charlie Muirhead and Neil Bradford. Muirhead is the 24-year-old founder of Orchestream, a software developer which has raised $32m in venture capital, while Bradford, 28, has seen his wealth take a quantum leap after his firm, Fletcher Research, was acquired by Forrester, the Boston-based internet technology research house, in May last year.

Both have made a pile of money, albeit mostly on paper, and can afford to take time off and indulge in an extended cruise in the Caribbean. But they are still hard at work and seem to have undergone little change in their lifestyle. In that sense, Muirhead and Bradford are no different from tycoons past and present. Rupert Murdoch trundles on, despite his advanced years. America's most controversial tycoon, John D Rockefeller, beavered away despite amassing colossal fortunes.

But why do they show so little inclination to pack it all in and become lotus-eaters? It seems that, besides enjoying what they do, the desire to keep on working or to stick to ventures in the field they know is probably a way of keeping grounded.

Bradford, who works out of an office on Charlotte Street in central London, still sports the classic new economy attire - Gap trousers and open-necked shirt. And he is clearly a man more at ease in talking about the future of the internet than about any lifestyle changes precipitated by his new-found wealth. Yes, he has bought a house, he says, but his interest in analysis of the internet revolution remains undimmed.

He appears lost for words when asked if he thinks he deserves his new-found wealth. After a pause, he says: "I don't want to say it was due to luck, because that would sound like false modesty. We had to work very hard."

But he does admit to occasionally waking up and feeling that the Fletcher Research success story is all a bit unreal. "Two years ago we were working in a converted warehouse in Ladbroke Grove on a shoestring, with a couple of computers, some phone lines, and relying on credit card funding," he says. "My friends had great jobs at great companies and we asked ourselves how long we could keep going, how long we could flog a dead horse."

Now it is probably their friends who are casting envious glances at Bradford and Will Reeve, Fletcher Research co-founder. They struck gold when Forrester, one of the world's most respected internet research firms, decided to buy Fletcher. The two now have Forrester shares by the bucket-load and enjoy a degree of security most people can only dream of. The biggest impact on Bradford, however, seems to be that he can concentrate on research, his forte.

"The job's changed," he said. "We used to muck in and do everything: writing, editing, researching. As you grow, your roles become more defined. People can concentrate on what they are best at."

While his professional world has been transformed, Bradford maintains that his personal life has changed little. "It's not as if I've dumped my old friends and party in Soho with glamorous models," he says. "I still hang out with my university friends, and people I've known for ever see no differences."

At Orchestream, Muirhead falls into the same category of new economy millionaires who prefer to keep their noses to the grindstone.

Orchestream developed a piece of software designed to ensure the reliable transmission of data along computer companies' networks and the internet, using the basic internet protocol (IP) technology that allows computers to communicate with each other over the net.

After that success, instead of resting on his laurels, Muirhead has started Igabriel, a network of angel investors that can help start-ups. The network builds on the extensive network Muirhead built up in his previous company's brief but rapid rise. Capped at about 100 movers and shakers - Brent Hoberman of Lastminute.com is part of the inner circle - Igabriel focuses on wireless and mobile commerce opportunities. The network says it has backing from a prominent private equity firm and intends to take on around 25 to 30 business plans a year.

Asked why he doesn't just stop to enjoy his money, Muirhead insists that he is not in it for the money.

'I want to do something for the people who are starting out now because I know what it was like for me when I started Orchestream without any contacts," says Muirhead. His ambition is to remain a "perpetual entrepreneur". Like Forrester, Muirhead makes the point that his ilk are driven by challenges rather than financial rewards. Money is clearly secondary to the buzz of being trailblazers in this hot but volatile sector.

Because fortunes in the UK internet sector are a recent phenomenon, these new millionaires have yet to lift their eyes beyond their immediate world. In the US, where new money is quickly acquiring the status of old money, internet millionaires have branched out.

At Cisco, the internet infrastructure company, quite a few of the new rich have started private family foundations with funds that range between $1m and £100m. Some foundations are designed to address specific issues such as cancer research or education. Others accept grant requests from any qualified non-profit organisation.

The biggest foundation, of course, is that of Microsoft's Bill Gates, who has turned philanthropist with a vengeance. Major donations to date include $250m to international vaccine projects through the Gates Foundation and a further $209m to endow the Gates Cambridge Scholarship Trust.

Given the way trends migrate here from America, it is likely that the new British e-tycoons will embark on philanthropic activities in their turn, especially as the chancellor, Gordon Brown, is giving them tax breaks.

Leading the way is one of Britain's earliest internet tycoons, QXL founder Tim Jackson. He has recently stepped down as a non-executive director at the online auction house to concentrate on his new venture capital role at Carlyle Internet Partners Europe and at a charitable foundation he is setting up.