Have you ever noticed that some pages on your site or blog aren't showing "real" adverts?
When Google doesn't "know" which adverts to serve they use Public Service Adverts. Unfortunately you won't earn a cent from these adverts, however you can specify an alternative advert in your adsense code.
A few months ago a service was launched specifically for this called Alternate URL. The adverts may not pay as much as standard Adsense ads, but they pay, which makes them a more attractive alternative.
You can signup here
When Google doesn't "know" which adverts to serve they use Public Service Adverts. Unfortunately you won't earn a cent from these adverts, however you can specify an alternative advert in your adsense code.
A few months ago a service was launched specifically for this called Alternate URL. The adverts may not pay as much as standard Adsense ads, but they pay, which makes them a more attractive alternative.
You can signup here