Adsense ads
Tip for all Christian bloggers: Be sure to keep an eye on the ads served by Google's adsense. Many Christian blogs are now running ads for a book claiming that Christ was invented after his death.
I put www.authorhouse.com on my adsense block list.
Whenever I see an inappropriate ad, I plan to click through and make sure it is innappropriate, and then alert the blogger to it's presence. This way I can get the URL to ban from my blog, and I get the blogger a few cents for his trouble.
Probably a bad advertizing stratagy for these companies in the long run. They are paying to get themselves blackballed.