The online advertising business is ready to enter a new era, as Google announced its latest service, meant to support advertisers in finding their specific target audience and better plan their business.

Up to this point, service like comScore and Nielsen Online have been offering Web measurement services based on surveys or by tracking what people do online.

Google’s Ad Planner is an improved Intenet data usage measurement tool, which should provide more consistent results, and is designed specifically for advertisers.

It may sound strange, but Google, who in turn is trying to boost its own ad-sales business, decided to make it all free. The consequence: comScore shares dropped 22.5 percent, to $21.45.

ComScore’s chairman Gian M. Fulgoni told the New York Times: “If I were a competitor of Google, the last thing I would want to do is use their products.”

And he doesn’t seem to be the only skeptic regarding Google’s move. Sarah Fay, chief executive of Aegis North America said, as quoted by The Wall Street Journal, that the last thing an advertiser would want to do is have their advertiser be the same person they are spending their money with.

However, leaving that aside, those who should be directly interested in the Ad Planner, the advertisers, are more than happy with Google’s initiative (at least a part of them). Others continue to watch Google’s move with caution.

Some ad executives have said that all in all, finding the right audience before actually placing an ad could boost the efficiency of the online advertising business.

The Ad Planner, which was officially unveiled on Tuesday, was created as a simple tool, which by introducing demographics and sites associated with a specific target audience, returns information about sites that the audience is likely to visit.

So far, we’ve seen the consequences of Google’s announcement on comScore. It still remains to be seen how many advertisers will actually begin to use the Ad Planner.

As some experts in the field have said, the tool is likely to attract smaller advertisers and businesses, and perhaps rivals such as comScore and Nielsen Online won’t lose their clients.

All in all, advertisers might find the tool useful, which is exactly the purpose of Google.

And despite the few challenges to the tool, which bases its measurements on cookies, the accuracy of the measured data is said to be greatly improved.