IT SEEMS there’s never been a better time to run a popular website. As the online world becomes hotter than hot again some of the most attractive websites are attracting very fetching prices.

The New York Times has just bought About.com for $410m (€310m) in cash. The deal comes hard on the heels of Dow Jones buying MarketWatch.com for $519m in cash, and the Washington Post paying an undisclosed sum for Slate, the online magazine.

Rumours swirl about the fate of TheStreet.com and Salon, Slate’s rival, which has just put out the first profitable quarter in its 10-year history.

There are solid financial reasons why America’s top newspaper groups are prepared to make big bets on online companies with shoddy profit records. Online advertising is expected to grow by 25% in 2005 following a similar 25% rise in 2004, according to the forecaster Universal McCann.

Major companies such as McDonald’s and Microsoft have increased their spending on the web. Total advertising on the internet in America in the final quarter of last year was expected to top $2.5 billion, the ninth successive quarterly increase. The total for last year topped $9.5 billion, according to the Interactive Advertising Bureau, well above the $7.3 billion in 2000 at the height of the technology boom. Newspaper advertising, by contrast, rose just 3.8% through the first three quarters of 2004 and is forecast to rise by just 4.1% in 2005, according to the Newspaper Association of America.

Dow Jones’s WSJ.com and the Times and Post’s websites are among the most heavily used in America so they are already getting some of the benefit of that resurgence in online advertising.

But there is a limit to how many people will subscribe to WSJ.com or want to wade through the New York Times or Post. New sites will bring new readers, the logic goes.

About.com is a sort of online how-to-do-it guide on everything from diets to motorcycles. It attracts more than 20m readers a month. The company has revenues of $40m a year and the New York Times will be hoping to pull About’s readers towards its other businesses. Don’t you just know that somewhere someone is using the word “synergy” again. It’s like the bubble never burst.

There are risks among this new enthusiasm. In MarketWatch, for instance, Dow Jones seems to have bought a business not dissimilar to WSJ.com. The Wall Street Journal’s impressive online business now has more than 700,000 paying subscribers. MarketWatch looks set to be largely free. The Journal’s readers are a savvy bunch — won’t they switch to MarketWatch if it’s any good? And if it’s not going to be competition for WSJ.com, what’s it for?

Newspapers groups don’t like to overpay and would never buy another newspaper at the top of the advertising cycle. But that is what they are doing now. Dow Jones paid $18 a share for MarketWatch. In the third quarter of 2001, MarketWatch traded at only $1.06. Why didn’t they buy it then?

Perhaps that’s a little unfair because, in a way, they did. The best time to run an online content business was just before the bubble burst. Back then all the major newspaper groups were spending fortunes only to see the money disappear in a puff of smoke. Now, having sold out or closed down their operations at the bottom of the market, they are buying their way back in at the top.