StreamCast Networks, distributor of the popular Morpheus software, is quietly counting the number of times its file swappers visit high-profile shopping sites. The company on Tuesday said it has begun installing a Web browser add-on that sends some Morpheus users on an invisible Web detour aimed at capturing data about file swappers' surfing habits. Thus, when a file swapper visits a site such as Radioshack.com, eBay.com or a handful of others, their computer visits a separate site behind the scenes before loading the final destination site. Those separate servers, run by marketing companies including Be Free, count how many times...