By BBC News Online's Kevin Anderson in Washington

How much would you pay for 30 seconds of fame?

At least a dozen Internet companies will pay up to $3m for 30 seconds of advertising time during the championship of American football, the Superbowl.

It is the highest price ever paid for television advertising.

In one case, Ourbeginning.com is willing to pay 400% of its 1999 revenues in an effort to make it the next cyber success story.

A year ago, only two "pure-play" Internet companies advertised during the Superbowl last year.

But this year in addition to the dozen companies advertising before or during the game, online brokerage E*Trade will sponsor the half-time show, according to Forrester Research, an Internet and IT consultancy.

Dot coms will represent an estimated 20% of the advertising during this year's Superbowl, says Forrester's Charlene Li.

Millions of eyeballs

The game holds a unique place in the world of advertising. It is the only television event in the US that can promise a potential audience of 135 million viewers.

Due to the high profile of the game, the ads have become an event unto themselves.

"Half of the audience watch for the game, and the other half watch for the ads," Ms Li says, adding, "it's one of the few events when people talk about the ads."

With that many attentive eyeballs, the crowd of dot coms is hoping to rise above the fray, with the dozen sites spending $25m on advertising for the game.

Big winner last year

Last year, Monster.com made a big splash with its ads during the Superbowl.

Traffic to the site after the game "brought their servers down to their knees", says David L Smith, with Mediasmith, an interactive media agency and media consultancy.

The ad kicked off a $40m campaign, and according to Media Matrix, Monster.com now has almost twice the reach of its nearest rival.

In the closest thing to conventional wisdom in the Internet economy, based on the success stories of Yahoo and Amazon.com, sites advertising this year hope to establish an early dominant position.

An early lead by a website has proven a barrier to entry for other companies wishing to launch a site in that market sector.

Crowded field

But unlike last year when Monster.com was one of only two Internet companies advertising during the game, this year, several dot coms will run ads.

That is in addition to the almost constant barrage of website ads on radio, TV, billboards and in print. It will be challenging for even these dozen sites to rise above the dot com din.

"With 12 ads (during the game), the dot coms will blunt the impact of each other," says Forrester's Charlene Li. Their Superbowl buys will have to be part of a larger, longer campaign, she adds.

And whereas Amazon and Yahoo had few challengers when they began, even small market niches are becoming crowded on the Internet.

Why bother?

Pets.com and LastMinute Travel hope to differentiate themselves in a packed marketplace, and it will take more than clever ads to win users away from other sites, says Ms Li.

The dot coms' ads have been "pretty ineffective," she says, adding that although the sock puppet dog for Pets.com is cute, it took her several viewings of the ad before she remembered the URL.

Sites must explain to viewers why "they should bother to boot up their computers, log on and go to the site."

Ms Li praised Lands End and the campaign for its website. The ad tells users that, unlike other websites, users can "try on" clothes using a virtual model and chat with customer support.

Shake-out

The dot com ad blitz began ahead of the Christmas shopping season and has raised the cost of entry into e-commerce.

Some sites secured a second round of venture capital funding just to pay for their ad campaigns, Mr Smith says.

And Charlene Li adds that start-up sites will use their Superbowl spots to prepare for stock market flotation.

Companies could use the money raised during their offerings to expand their business and increase their ad spending.

Sites are increasing their advertising budgets from $5-7m each last year to $30-50m this year, says Mr Smith.

Forrester Research says sites will be forced to buy pricey ad time during major events such as the Superbowl, the World Cup and Olympics in order to break out of the new media pack.

Companies not able to raise the money for mass media advertising might find themselves lost in the dot com clutter.