Here's a neat little tip I've utlized to great effect.

By utlizing PhpAdsNew and an adserving page on your site you can simply specify the url of the adserving page as the default page in Adsense so that if it can't serve any targetted ads it will serve your adserving page which includes you optimized and targetted sponosor ads. This way you don't lose a single opportunity to sell to a customer.

Give it a go. And if anybody needs any more help or advice on this just hit me up.

Regards

Lux