WASHINGTON POST - Feb 14 - Justin McLeod recently started a D.C.-based mobile dating app called Hinge, which lets users rank and connect with their friends’ Facebook friends. Every day at noon, Hinge users who sign up using their Facebook accounts receive a batch of 25 profiles of potential matches collected from a pool of their friends’ friends. Users rank the profiles on a scale from 1 to 5. If two people rank each other at 4 or 5, Hinge sends a “match” introduction to both. Hinge’s algorithm weeds out users who are listed on Facebook as married or in a relationship, who aren’t local, and who are out of users’ desired age range. Since its launch last week, Hinge’s app has been installed a couple thousand times. The app has already produced ~600 matches.