I just loaded up the front page of the blog and noticed that the ad at the top was for voting Yes on California's Proposition 8. I am actually strongly opposed to Prop 8, which would eliminate the right of same sex couples to marry in California and was dismayed to see the ad there at the top of the page. It points out one of the risks of using Google's Adsense ads: they are based on "keywords" in the content of the text on the page. Usually that works pretty well, but there is no guarantee that the advertisers who have bid on a particular keyword or keywords are advertising something you'd actually want associated with your site.
I've banned the URL of the "Yes on 8" site from my ads, and that should stop the ads within the next 10 minutes.
(The Yes on 8 people must have bid on a lot of different keywords, since the Yes on 8 ad is appearing both here and on my "Women in Science" blog, and on a couple of other non-science fora I frequent. Weird.)
ETA: Now I've surfed around and I'm seeing those "Yes on 8" on almost every site with Adsense. I wonder if they are being served to me because I have a California IP.