His latest venture is called deckchair.com and offers bargain basement flights on the Internet.

The BBC's Sarah Boxhall reports on booking a holiday on the Net

Mr Geldof, 45, said the idea for the site had been born out of frustration at being unable to find cheap airline tickets when he had wanted to take his children on holiday to Florida last summer.

He said: "I get really irritated and impatient and irascible when I can't do simple little things like get a cheap flight."

Come fly with me

That frustration spurred him on to team up with James Page, one of the founders of Eidos, the computer games group, who helped develop the software for the site.

The singer says deckchair.com will be free of jargon and quick and easy to use.

Sir Bob the travel agent

He said: "You say where you want to go, press a button for the cheapest flight that is available at that moment, type in your credit card and a couple of days later you get a ticket, that's what it does.

"It scans five million available fares in 45 seconds on average."

However, deckchair.com faces stiff competition from established sites like bargainholidays.com and Microsoft's Expedia which launched in Britain last November and already has 260,000 customers. A revamped Thomas Cook website is also set to be launched later in the year.

Joseph Gagnon, a member of the e-commerce team at accountants Ernst and Young, said: "The e-commerce market will thrive from greater choice, we welcome any competition that is out there to work alongside Microsoft Expedia."

At the moment, the number of people booking holidays through the Internet is still small.

According to the latest Mori poll, only 0.5% of holidaymakers have booked flights online.

A further 35% plan to at some time in the future but 25% do not envisage using it at all.

Technical hitches

But evidence that the market is expanding rapidly is proved by some of the teething problems experienced by deckchair.com on its first day of operation.

Mr Geldof admitted: "Unfortunately since six o'clock this morning there are all these Herberts going into work with nothing to do and checking out the site.

"We are getting something like 1,500 hits which is frankly breaking the back of our one steam-driven computer in the office.

"It probably won't be able to handle the burden of so many questions simultaneously, so our normal response time of 45 seconds will be longer, which is a drag."

But the deckchair.com team remain convinced that booking flights over the Internet is set to boom.

Mr Page said: "In America, one of the online travel agencies is the 20th largest in the States."

The rock star is no doubt hoping to repeat the success of his last business venture Planet 24, the television company that produced The Big Breakfast and The Word.

It was sold to Carlton Communications last month for an estimated £18m, with Geldof thought to have made about £6m on the deal.