I'm not sure what the % increase would be based on your demo information. I know that the more targeted your ad space, the more it could be worth to an advertiser trying to target that demo. On the other hand the less it would be worth to someone that is not trying to target that demo.

If I were to guess, the information you provided in your post would bring more of a 10-20% increase over just saying "I get 1000 unique visits a day". But if you were to go to Cingular and say "I get 1000 unique visits a day that are all shopping for cell phone service" you could greatly increase your ad space revenue to Cingular, maybe 50% or more.