Scareware, fake security software, is getting more and more prevalent.  The revenues from scareware, are outpacing the revenues from spam. The FBI has recently put the number at $150 million stolen via scareware.

One of the most prevalent method is Blackhat search engine optimization.  In this scenario, web pages are generated with a huge list of keywords (often relating to current events), so that they rank high in the search engines.  If a user clicks on the link from the search engine, and visits the page, they are automatically redirected to a fake real-time anti-virus scanning screen.  Of course the result is always that the computer is infected, and you need to buy their software to clean it.

If the user is intimidated into purchasing the "software", they do not get any real protection for their money.  In addition, their credit card information is now in the hands of the criminals, to do with as they please.

So, remember, just because a page ranks high on your favorite, and legitimate search engine, does not mean that it is safe.  You need to be alert to these scams, and always be suspicious of any offers.