A friend recently forwarded a piece to me that pointed out that the good folks at Google may be raking in upwards of $500 million per year...because of your (and my) mistakes. A "typo," to be precise.

Google may be earning an alleged $500 million a year via companies and individuals who register deceptive website addresses.

The claim centres on a controversial scheme known as “typosquatting“, the practice of registering a misspelled variant of a popular web domain. For example, a typosquatter might register “newscientsist.com” in the hope of getting visits from people who meant to type “newscientist.com”.

If that mistake is made frequently enough, the owner of newscientsist.com can profit by placing ads on their page. They could, in particular, use Google’s advertising network which automatically assigns ads to a page based on its content, or using keywords provided by the page’s owner.

I think we've all been there. You're in a hurry, you type in the web address, and then you wind up somewhere not even close to what you were anticipating. Tyler Moore and Benjamin Edelson of Harvard University crunched some numbers:

Moore and Edelman started by using common spelling mistakes to create a list of possible typo domains for the 3264 most popular .com websites, as determined by Alexa.com rankings. They estimate that each of the 3264 top sites is targeted by around 280 typo domains.

They then used software to crawl 285,000 of these 900,000-odd sites to determine what revenue the typo domains might be generating.

If the top 100,000 websites suffer the same typosquatting rate as the sites Moore and Edelman studied, up to 68 million people a day could visit a typo site, they say. They estimate that almost 60 per cent of typo sites could have adverts supplied by Google.

If the company earns as much per visitor from ads on typo sites as it reportedly does from ads alongside search results, it could potentially earn $497 million a year in revenue from typo domains, they conclude.

Google’s total 2009 revenues were $23 billion, 97 per cent of which came from advertising.

Take a look at a few other cases where a typo cost someone some serious cash: