Behaviorally-targeted advertising is more than twice as effective at converting users who click on the ads into buyers (6.8% conversion vs.2.8% for run-of-network ads) according to a new study by the Network Advertising Initiative (NAI). Based on proprietary data from twelve major ad networks, the study found in 2009, behaviorally-targeted advertising pulled in an average of 2.68 times as much revenue per ad as non-targeted advertising.