Only about a year and a half too late . . . finally search engines are getting together to do some PR and fight click fraud. According to AP/BostonHerald.com:
The initiative, to be announced Wednesday morning by the Interactive Advertising Bureau, will draw upon the expertise of Google Inc., Yahoo Inc. and Microsoft Corp. – the owners of the top online search engines – to attack a problem threatening to erode their profits. Combined, the three companies control 86 percent of the lucrative U.S. search engine market, according to comScore Media Metrix.
Two smaller search engines, InterActiveCorp.’s Ask.com and LookSmart Ltd., also have joined the alliance along with the Media Rating Council, a nonprofit group formed 42 years ago at the urging of Congress to help track and validate the sizes of advertising audiences.
Finally!
Here’s more from Elinor Mills at CNET.
Screenwerk 
August 6, 2006 at 7:15 pm
Click Fraud is an interesting topic – one which both clicktracks and adwatcher will stop, one which will cost you an estimated 20% of your ad budget.
This is an interesting article with valuable information. I have used both clicktracks and adwatcher to prevent clickfraud. What we and many other webmasters are starting to do is invest our marketing dollars into clicktracks, adwatcher or other ad tracker software.
If you are looking for more information on adwatcher or clicktracks i recommend you take a look at: http://www.trackingsoftwarereviews.com they have full reviews on both clicktracks and adwatcher!
Mike Baker