The thing I learned today from the Eclectic Economist

There are click fraud experts.

And from Tom Hanna's comment: "I use my blog for testing new features that I'm going to use on more important sites and so I've fiddled with Adsense a bit. Blog revenue is considerably lower for the same amount of traffic than non-blog webpages no matter what I do, but I get three to four times the revenue out of running a 468x60 banner at the bottom of each post compared to running ads in the sidebar. I think you can modify your template on Blogger to allow you to do the same thing. A blog still isn't going to get anybody rich, but 3x the cash is a few Big Macs anyway."