The inimitable John Gruber shares his traffic numbers, as background to why he dropped Google Adsense and now sells his own sponsored placements.
He does 6,000 page views per day, and finds that his Google AdSense numbers match his server log numbers pretty closely. Google has historically counted mine a bit low, for reasons I’ve not understood (about 7:1 low). My daily average page views since Jan 1 are 2,736, while Google puts them at 391. The graph below tells the tale: other than that weird spike August, things have been reasonably steady but declining, especially after I switched to WordPress. Oddly, traffic volumes increased since then.
I expect part of the problem is the large amount of robot/search engine crawler traffic I see. Obviously, they’ll count as page views but will not call up any ads to be served. But that doesn’t explain the decline since WordPress was implemented . . . . there’s something about dynamic versus static pages that seems to be a problem. I don’t know what difference it could make, unless GoogleBot doesn’t grok query strings in it’s indexes (I find that hard to believe, though).
For comparative purposes, here’s the logged traffic, page views only (I don’t log images, css files, or xml files associated with RSS subscriptions). 
The difference is partly attributable to robots that don’t load the ad content, but the decline in the post-WordPress days is harder to explain.
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