The social-networking companies’ early successes will be solidified if they can figure out the answers to a few open questions. One is about cooperation. Today, if consumers or businesspeople want to tap into online social networks maintained by different companies, they must fill out new profiles and send out new connection invitations in each. But many users wish they could make their networks larger and more varied by creating connections across the boundaries of sites like LinkedIn, Ryze, and Tribe. A data standard being developed by independent programmers called “Friend of a Friend”-a way to create a short, machine-readable file that resides on the Web and provides your personal data and the names of your connections to any software that requests it-promises to make such internetwork connections easier, but it has been slow to roll out.