Clicktracks is well known as a significant player in the analytics space, and is in particular well known for the click fraud analysis tools that they provide to their clients as part of that package. Recently the Clicktracks CEO, John Marshall, and I spoke about click fraud in a podcast we did together.
John provides an excellent overview of what click fraud really is, how pervasive it is, and what the search engines are doing about it. For example, John outlines that click fraud affects sites in a very random manner, where some sites are hit very hard by it, and others not at all. John also indicates that the problem is much worse in very competitive markets.
When I asked John if the search engines were doing enough to combat click fraud, he provided an answer that will surprise most people (the answer was "yes"). John is not minimizing click fraud when he says this. He is simply saying that it is incumbent on the advertiser to play an active role in combatting click fraud as well.