If you've been ripped off by Google AdSense (ie: account terminated due to invalid clicks) I can only advise you to try to be firm and polite...
If it doesn't work, try
AdBrite.
Not just click sabotage and accidental clicks can stop your ads though (small digression)...
A year back I ran a site which published the
Mohammed cartoons (amongst other).
The site was doing quite well with Google ads, until a muslim fundementalist organisation e-mailed Google AdSense and managed to stop the ads. I don't know what they wrote, and probably never will. The reason I found out that it was this organisation, and not Google, wich was behind it was through an online muslim newspaper.
Google emailed me and told me that I had "content that infringed with their adsense terms." I politely asked them to point out what content they were referring to, and was only met by a few vague paragraphs from their T&C (further correspondence not returned).
Luckily, they just stopped showing the ads on the site and never cancelled my account. I also receieved my earnings for this and my other sites on schedule. I have been with them since, and used them on many other sites (far less popular and controversial though) and I'm happy with them, afterall.
Contextual ads are great, but Google totally lacks backbone!