Google's Adwords are a revelation in internet advertising, directly linking to ads that are (mostly) relevant to the topic you are viewing.
However, here is a story detailing one progressive website's battle against the Google Adwords editorial board.
Google apparantly dropped their ads due to "language that advocates against an individual, group, or organization". However, this broad brush pretty much removes any sort of journalistic or religious website from their ads, as well as any blogs. And it appears that Google has a little bit of bias when it comes to which ads need removing:
Given the recent flaps over the apparent double-standard in prime-time advertising at CBS (running virulently anti-Clinton ads by the right-wing Citizens United, refusing to air ant-Bush ads by MoveOn during the Super Bowl), I was immediately suspicious of anti-liberal bias by Google towards advertisers. Doing a quick check, I found no shortage of conservative advertisers currently on Google that made me seem like Mother Theresa in comparison.
Liberal sites' ads seem to be getting removed while conservatives sites' ads seem to be remaining. Though it's hard to tell if this is calculated on Google's part, or just another media outlet that got deluged with complaint letters from conversative viewers. Either way, the effect is the same.
Several progressive blogs on my daily read list use BlogAds instead, which are perhaps much more appropriate to political blog readers themselves. Guess we have another good reason now why BlogAds was a better decision.