Check out the NRA's 19-page blacklist of groups, businesses, and celebrities with "anti-gun" policies.  Keep in mind that supporting gun safety measures such as mandatory safety locks is enough to qualify as "anti-gun."  Among the members of this list are the National Education Association, the League of Women Voters, and my beloved St. Louis Cardinals.  At this point, I think more people in the United States belong to or support one of the names on this list than are left to boycott them.