Chitika Research,”a full-service on-line advertising network serving over 2 billion monthly impressions across more than 80,000 websites,” has been closely monitoring the sales figures of the Apple iPad since its release into the wild on April 3rd. Chitika is basing its volume estimates on the number of unique iPads connecting to the Chitika ad network, which can be tracked in real time here. At time of article publishing, the ad network estimates that over 511,000 iPad have been sold by Apple. Since Chitika’s sales estimates are based on the number of iPads that have been turned on and connected to the internet, as opposed to Apple’s number which includes “deliveries to channel partners,” the Chitika number could be more accurate then the numbers coming out of Cupertino. We say “could be more accurate” because those who purchased an iPad over the weekend technically could have waited until Monday or Tuesday to fire it up for the first time — although, we don’t understand those kind of people. What do you think? Still not as impressive as the 700,000 figure that Mr. Munster threw out there… anyone ready to call the iPad launch a success or failure yet?