As the editor/publisher of a content site, I'd like the ability to have a "Buy an ad" link for Adsense on my site.
When the prospective advertiser clicked on the link, he'd be taken to a Google AdWords form that would allow him to:
1) Buy an AdWord only for my site;
2) Buy an Adword for my site plus Google Search;
3) Buy an Adword for my site, Google Search, and the entire AdSense network.
This would be great for me, because I have no desire to get into advertising sales but would like a way to sell ads.
It would also be good for Google, because it would provide Google with referrals and it would promote sales of AdWords on content sites.