Balancing reach with relevance is critical for behavioral targeting campaigns. Being able to see how an audience size is affected by the targeting parameters being set for a campaign and make real-time adjustments before the campaign launches or during the campaign to get optimal results is helpful. Revenue Science has developed a tool that lets advertisers do this.

What is needed is a way to map audiences across the web to aggregate the micro-niches that behavioral targeting makes possible and yield a higher potential customer count.

The problem isn't the precision with which you seek your audience, per se, but that they might not live in large enough groups at any one place to make the business sense to allocate resources that reach them.