According to a couple of Harvard University click counters, Google could be earning close to half a billion dollars a year out of adverts placed on typo-squatted sites.
The Harvard researchers Tyler Moore and Benjamin Edelman say it is "difficult to know exactly how many people visit typosquatting domains."
That doesn't stop them having a go and providing estimates of the number of visitors reaching typo sites (thinq www.microsft.com) as well as the fees advertisers pay to Google.
The researchers' site traffic data comes from Alexa, which makes the estimates even more of a guess. But, on average, visitors to a site's typo domains total 0.7 per cent of visits to the genuine site, they reckon.
Extrapolating this percentage to 3,264 popular sites studied, the pair estimate that typo domains collectively receive at least 22 million daily visitors.
If these typo domains were treated as a single website, that site would be ranked by Alexa as the 36th most popular website in the world.
Armed with this estimate and an assessment of how much Google's Ad sense earns out the sites, the researchers estimate that Google's revenue from typosquatting on the top 100,000 sites is $497 million per year.