The arrival of the first post-Christmas credit card bill may have led many to think about ways of making extra money.

There are many offers to earn thousands of pounds for just a few hours a day. This usually means parting with a lump sum, or there is pyramid selling household goods or make-up door-to-door.

The Internet has moved in with the promise of money simply for surfing.

It is all to do with advertising revenue. Surfers are paid to look at adverts and to get others to join them. There is an amount for each click and for each person referred to the ads with follow-on commission for the people they in turn refer.

Depending on the company, a surfer can be paid through as many as half a dozen levels of referrals. The same holds for receiving and sending e-mails.

The only obvious catch in all of this is that you do have to watch some of the ads and have your computer gummed up with large files.

There are people out there on the Net offering to help – completely free – to maximise your earnings. MaxRef is one. It has an Internet site and promises to help you work with only the most profitable.

From these it will get you plenty of free bonus referrals and ensure the people upstream of you are the most successful and will pass down lots of lucrative leads.

Earning money by surfing is becoming popular. Many see it as a hobby that pays and most agree that the more effort you make, the more you earn.

How much? A few hundred quid a year it seems, although there can be top ups from free goods and services.

There are various methods. A popular one is to view adverts. Companies pay a varying amount, but the higher the rate, the more strings. A common rate is 50 cents an hour with a limit of 20 hours per month. Referrals are usual 5 cents for the first one or two, reducing to 1 cent and often limited to three or four referrals. Some have lower initial rates but higher referral rates.

Then there are contribution sites, where users get paid to make an opinion – usually about a product, such as a book, CD, concert or film. This is usually restricted to UK sites, by the nature of the product, and pays 25p an opinion and 50p every time it is read. This could be recommending a book and linking it to a site such as Amazon where it can be bought.

One person has made £300 doing this, and recently netted £25 in a quarter.

There is also e-mail, where you are sent e-mails or send e-mails that carry an advert. One person recently said he earned a tenner.

Then there are the promotion sites where there are give-aways or competitions, such as concert tickets or champagne, again in return for a recommendation.

The view of many of the fans is that it is nice to be paid for a hobby, although many surfers warn of computer crashes and that much of the free stuff is not worth having.

There are some people who try to make it a career – not least by hosting their own version of MaxRef and trying to get upstream of everybody else.