B.L. Ochman thinks online social networks need to promote offline gatherings similar to the Utne salons.

"MoveOn.org, which organize house parties, picnics, protests and meetings via the Internet. In fact, this type of political action combing the Internet and the outernet has revolutionized politics. And it will work for lot of other companies that want direct connection with their customers.

About 15 years ago Utne Magazine started the Utne salons. It required elaborate planning, much phone calling, faxing and mailing to start and join a salon in your neighborhood. Hundreds were formed, including one I joined, and many wonderful associations were begun."

"……people hanker for face to face contact with kindred spirits. A wonderful thing happens when people with much in common meet in person. They eat and drink together, make deals, fall in love, form deep friendships. Nothing beats face to face for niche groups. And that’s a huge opportunity for companies that really want to join the conversation and not just pay lip service to it.."

B.L. identified that online social networks are can and often should promote offline meetings. The only way I’d know to tie this into web metrics is to count the percentage of times where an online contact results in an offline meeting.  I’m not sure all online niche communities can result in offline meetings so this metric would not work in every instance.