Times are certainly changing. Was it really only a few years back that the internet was primarily the domain of low-end tech-savvy users and the only celebrity endorsements we were privy to were the likes of Nanette Newman touting Fairy liquid? Nowadays, it seems that wherever you look on the web you can't avoid stumbling across famous names endorsing a new website or throwing their weight behind their own new internet venture.

The reasons are obvious: most celebrities hanker after any kind of media promotion and if getting involved in an internet venture also manages to give them additional kudos, then that has to be a good thing. The glut of coverage at the start of this year about the fame and fortune that the internet brings only served to encourage the feelings of dot.com envy, and even though this has been replaced recently by feelings of dot.com disenchantment, the internet is still seen as a future-proof investment strategy.

The latest entrant into this territory is Clive James, antipodean journalist-cum-TV presenter. James is not ready to shy away from what, in his words, represents his next big challenge. At a press lunch in London two weeks ago, James touted the wares of Welcome Stranger, an internet start-up aimed at people who travel.

Having managed to pull off a fine performance selling his involvement in Welcomestranger.com at the lunch, James then set about telling us that the company needed £500,000 to move the business on to the next stage. Nothing like pulling a fast one by looking for coverage before the funding is settled, he admitted, upsetting some of the more cynical journalists present.

James's involvement with Welcome Stranger, a planned network of sites for travellers in different cities and countries, may be as little more than a figurehead non-exec chairman. But it is a canny move on behalf of the company's founder, Simon Larcey, who is banking on James' name to generate both media and investor interest. In return, James gets a share in the company and the chance to promote his books and himself through the network of sites. Larcey's plan seems to be working. Immediately after announcing James's appointment, several investors got in touch and he is currently pursuing talks with them.

"It's great working with someone like Clive," he says, "because it automatically gives Welcome Stranger a profile. However, we still have to prove that we have an attractive business model to potential investors to raise the funding and that's my job."

For the past year, Larcey has painstakingly been building the infrastructure for his websites, convincing IT and advertising friends to work for him in exchange for equity stakes. He projects that the business will be in the black within three years via a combination of advertising revenue (beer, job and airline advertisers are proving particularly enthusiastic) and e-commerce revenues.

In convincing James to get involved, Larcey has inadvertedly catapulted him into an area increasingly over-populated with famous names: Joanna Lumley (ClickMango.com), Hugh Scully (QXL), Boris Becker (Sportgate), Bob Geldof (Deckchair.com and WapWorld), Jonathan Ross (toyzone.co.uk) and Alex Ferguson (Toptable.co.uk) have also taken stakes in ventures in return for providing publicity.

Narda Shirley, managing director of Gnash, a new media PR and marketing consultancy that handles PR work for ClickMango, says: "Celebrity endorsement can be the best or the worst thing to happen to a website depending on your personal perspective. How many 30-plus cyber-savvy new mums can relate to Melinda Messenger? But there's no doubt that the right celebrity involvement conveys credibility to consumers and helps a company stand out from its competition. What's interesting is how some companies have gone beyond pure personal appearances and endorsements to make the celebrity an integral part of the user experience."

For a reputed 2% share of the company, Lumley was not just its figurehead but also worked tirelessly on "road-testing" new health and beauty products. Her efforts were then converted into a weekly newsletter called "Joanna tries out..."

Unfortunately for Joanna, being a figurehead for a start-up meant that once cracks began to show, she had to take some of the blame. Most media outlets had a field day, waxing lyrically about how Lumley was dropping out of the net, and how even someone as high-profile and well-liked as her could not sell products. At the time of announcing its impending closure, ClickMango had a reported turnover of just £2,000 a week.

Perhaps the overriding image of Lumley as a chain-smoking, alcohol- and drug-abusing wreck in Absolutely Fabulous was too much for people to bear. Or perhaps it was just down to market conditions.

But while the company is still holding out for a last-minute reprieve, it is reassuring to know that Lumley is not deserting the sinking ship. She is said to be doing wonders for staff morale over at ClickMango, but not even someone as famous as Lumley can convince investors to stand by an ailing start-up.

Hugh Scully's involvement in QXL is as a little more than a figurehead: he runs the World of Antiques section of the site, which plugs into 22 antiques experts. The site (www.antiques.qxl.com), launched at the start of April, offers QXL members the chance to get their valuables valued at £12 a time.

Scully was paid £3m in shares when he signed the deal in October last year, although the bulk could be sold only once the site was launched - and by then QXL's share price had plummeted to less than half its October value. The idea behind Scully's involvement was twofold: to give QXL more credibility in the auctions world and to attract a different, older audience to the website. Whether this will work remains to be seen.

James's involvement in Welcome Stranger is slightly less promotional and more at board level, getting involved in quests for funding, attending strategy meetings and piggy-backing its traffic to promote his books.

The company, which has already launched aussieinlondon.com, is looking to expand its operations to include kiwiinlondon.com and bokinlondon.com, similar sites for New Zealanders and South Africans - and to offer generic features such as job and accommodation ads and advice on travel and visas.

Admitting to taking a stake of less than 10%, James says one of the main attractions was the way in which the web allows him to reach the public directly "without having to fight with the TV networks".

Part of the reason dot.com start-ups have been quick to sign up celebrities is that they want to stand out from the crowd. The more crowded the sector you operate in, the more important a well-defined brand becomes, and although Welcome Stranger has an unusual business model, the publicity a famous name gives a new venture is not to be sniffed at.

But choosing a celebrity is always a gamble - in the worst-case scenario, your figurehead could do irreparable damage to the brand. "Celebrities can beef up your brand appeal enormously but the challenge is to find one whose public persona and attributes are really firmly entrenched," warns Narda Shirley. With more and more famous names using new media as a promotional vehicle, it's surely just a matter of time before a celebrity's antics kill a dot.com business.

James accepts that getting involved in a new media venture is a bit of a gamble, especially in the current climate and having seen Lumley become the scapegoat for the problems over at ClickMango. But, having learnt from his experience in the cutthroat world of TV production, he reckons this one will work: "Celebrities are staking their prestige on these internet ventures. It's too late to play dumb. I wouldn't be in this if I didn't think it would work."

On your head be it then, Mr James.