Regarding AdSense — while I’m not in that department and definitely can’t speak for them officially — you might want to try page area targeting (or whatever they call it) if you haven’t already… specifying exactly what portion of your page content (e.g., blog body, not nav area) should be used for contextual clues. I remember this being at least moderately helpful when I used AdSense on my own blog a year or so ago.

Also, if you notice targeting being wildly off and consistently so, drop the AdSense folks a note at adsense-support [at] google.com. It’s my recollection that they can tweak something to improve relevancy in certain situations.

After all, everyone wins (advertisers, Google, and you) when the ads are more relevant. Not that there’s anything wrong with Christmas trees, of course