Interesting tidbit from http://adsense.blogspot.com/2008/04/promoting-your-referrals-properly.html :
<< if the primary purpose of your site is to generate conversions from referral ads, you'll need to go one step further before advertising your site. You'll need to first receive permission from the advertisers whose products you're referring before advertising your site or their products. Please note that Google has made the decision to not allow publishers to use online advertising for any of the Google products or those of our Google Pack partners. >>
That means the ads for sites that refer Firefox + Google Toolbar or Google Pack are no longer allowed. I suppose this was a profitable business: pay 20-30 cents for the ads and earn up to $1 from Google.
http://www.jepstone.net/blog/wpcontent/uploads/2007/08/molzia1.jpg |