As anyone who’s whiled away an evening “pinning” can attest, Pinterest is something of an addiction. Millions of users can’t seem to get enough of the 3-year-old social scrapbooking site. The latest Pew Research Center poll shows Pinterest is nearly even with ­Twitter; each site hosts about 15 percent of online adults—most of them female. As of September, comScore counted more than 25 million unique visitors on Pinterest, up from the 11.7 million it counted at the start of 2012. Pinterest doesn’t talk numbers but some sources estimate the site has some 50 million users. To put that figure in perspective, Vogue—the most influential fashion magazine in the world—counts a total circulation of about 1 million. And ­Pinterest’s referral traffic recently surpassed Google’s, according to the online sharing service Shareaholic.© Larry StanleyWhen Jewelry Studio in Bozeman,