Google Ad Planner

To add a new notch on the Google's plot to take over the internet, check out AdPlanner.

I read about this first in the Google Agency Fortnightly Update (which I'd recommend you sign up to.. let me know if you need help with access).

"To make your life easier, we're introducing Google Ad Planner, a research and media planning tool that connects advertisers and publishers. When using Google Ad Planner, simply enter demographics and sites associated with your target audience, and the tool will return information about sites (both on and off the Google content network) that your audience is likely to visit. You can drill down further to get more detail like demographics and related searches for a particular site, or you can get aggregate statistics for the sites you've added to your media plan."
-http://adwords.blogspot.com/2008/06/introducing-google-ad-planner.html

Right now it's open by invite only (I'll keep you posted should I get invited and if it actually is helpful). I'm guessing that it will be more helpful than NNR, at least in time.

You can go to https://www.google.com/adplanner and have a play, but it currently seems to only include uniques, reach, page views by site (and by state). You can add some layering like 'keywords searched' and 'sites visited', but I'm not really sure what that means at this point.