I have used many, including all mentioned above, clickguard works the best, in my opinion, allowing you to set rules based on behavior, campaign, ad group, keyword, etc. I disagree with the above comment that, controlling with rules doesn't work. Although, I wouldn't recommend using any of them. I have seen this question almost more than any other. There are other safer more profitable ways of managing who clicks your ads. What makes you think you need fraud protection?