Continuing its inroads in the media planning side of the business, Google (NSDQ: GOOG) will launch an ad planning tool for agencies and marketers tomorrow called AdPlanner. According to NYT, “AdPlanner, was designed to help agencies identify sites where their target audience might be active. While it uses audience measurement data, AdPlanner also combines it with search engine data and information from third parties, to determine with more precision what sites attract a certain demographic audience. It then uses that data to help agencies determine where to place ads.”

The tool is expected to be free, at least for now, the story says. This service is intended to be in competition with the ones offered by traditional online measurement firms such as comScore (NSDQ: SCOR), Nielsen Online and Quantcast.