In an aggressive bid to entice prospective “sex tourists,” the Department of Homeland Security last year launched an undercover web site that purported to arrange trips from the U.S. to Canada, where clients could engage in sexual activity with minors, The Smoking Gun has learned. The “Precious Treasure Holiday Company” web site was active until a few weeks ago when its Massachusetts-based web hosting firm removed the site from its servers, apparently in response to a complaint about its content.