Denmark has a problem: At some (still quite distant) point in the future, its population will disappear because people aren't having enough babies. Now, the Danish travel company Spies says it might have found a solution. Its campaign "Do it for Mom" encourages wannabe grandmothers and grandfathers to "sponsor" trips abroad for their adult children. Studies have shown that Danes have much more sex when they are on vacation. "Send your child on an active holiday and get a grandchild within nine months," the company says on its Web site. "The Danish welfare system is under pressure. There are still...