iPad sales have already cracked the 500,000 mark with less than a week on the market, an estimate by Chitika found today. Basing it on the amount of new iPads connecting to Chitika's ad network and accounting for the company's share of the market, it believes that over 530,000 of the Apple tablets have been sold as of Wednesday night. The prediction would have Apple almost doubling its 300,000 launch day units and passing that figure by the end of the week or sooner.
