Google AdSense for parked domains allows domain name registrars and large domain name holders to deliver targeted, conceptually related keywords and advertisements to parked domain name pages.

Google AdSense for domains’s powerful semantic technology dynamically analyzes domain names and displays targeted ads and related searches based on the meaning of the domain name. The ads are derived from the Google AdWords network.

AdSense for domains customers redirect traffic from parked domain names to the AdSense for domains service, which returns formatted HTML that includes contextual ads and related searches and even XML output for large customers.

Your network of sites should generate 750,000 page views per month to be eligible for the AdSense for domains service. This a unique way to make extra money from your parked domain names. I suppose several big domain name registrars are already using this service.