Google Ad Planner: Helpful in Media Planning

Recently Google has introduced Google Ad Planner, which is 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 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.