People will be paid to read their e-mail as part of a service designed to let companies bring more targeted marketing to customers.

Reading a single e-mail will earn a user 25 cents - with an annual windfall of up to $400 (£196), though the price would vary depending on a recipient's earnings and their attractiveness to advertisers.

The service, called Boxbe, already works with a range of web-based e-mail services, including Yahoo! and Gmail. As well as paying customers to read their messages, it provides an e-mail filtering service.

Unlike traditional e-mail-based marketing, which is often an unwanted result of e-mail address falling into the wrong hands, users would sign up for Boxbe and offer personal information which would allow marketers to further customise messages.

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An e-mail user earning $50,000 a year could expect to bring in around $100 a year, while someone with a salary $200,000 could expect to get $400 - just for opening his or her inbox, the company said.

Users could also set a minimum fee that they want to be paid for reading a single e-mail based on the topic of the mail and its relevance to them. "If you were Bill Gates, you could probably set your price at $40 per e-mail and people would probably be willing to pay," said Thede Loder, founder and chief executive of Boxbe.

If the topic was of limited relevance to a user, they might raise the price to be sent an e-mail about it, whereas messages on topics they were interested in they might accept for a lower fee, Mr Loder said.

US companies spent $40 billion on direct marketing by post each year, Mr Loder said, of which $20 billion alone went on stamps. "The marketers like our service because they think of it as money that would otherwise be going to the post office now going to their customers."

The information provided by users would be anonymous, offering marketers only a 'profile' of the user, and fake e-mail accounts designed simply to gather cash would be weeded out by close monitoring of how recipients responded to messages.

Boxbe was one of a number of newer companies giving presentations at Web 2.0 Summit, the world's largest internet conference, in San Fransisco.

Others to be given a platform at the highly soughtafter 'Edge' event - a showcase of 'web companies of the future', included Meebo, the popular web-based instant messaging service, and Virgin Charter, the booking service for private jets backed by Richard Branson that is due to launch in February next year.

One presentation that generated a lot of interest was by Topix, a site that aims to brings together content relevant to local areas form a range of news sources.

The site's chief executive, Chris Tolles, said that despite local services accounting for 60 per cent of the total ad spend in the US - about $97 billion - very few websites provide locally targeted content that is interesting to advertisers selling local services.

Topix collects stories from a range of local news sources - including newspapers, radio and other websites - that are relevant to a particular locale or post code, providing an enticing platform for advertisers, he said. The site also had other services, such as comment and chatrooms, designed to create 'local momentum' around events.

"Even Craigslist, which launced in 1995, still only caters to about 300 plus cities," Mr Tolles said.

"We aggregate more than 22,293 local news stories a day, and are also able to generate interesting, civic discussion in more than 20,000 forums."