The reason I ask: A friend of mine is the chairman of a gliding club. When he became chairman he identified a couple of key problems, new members felt that it was cliquey and hard to get to know people. Also each meet needed a minimum number of people to operate equipment, but members didn't know who was going, for example one or two with the necessary skills would turn up but not enough to operate winches etc and everyone would have to go home. Facebook was a possibility, but most members are over 60 and many are not into facebook, or find there is too much information and advertising on Facebook.
Do these problems sound familiar?
Anyway he signed the club up to social networking site meetup.com. It's a subscription model and no advertising, but rates are low. He spent lots of long nights on the phone persuading most of his club to sign up/create a profile, including a photo and a few words about them. Creating events is the main thing with meetup, so now whenever someone plans a gliding meet, a meetup event is created and people say they go. Newcomers find it more welcoming because there are pictures, and established members get to see the photo of the new member before the event, so are more likely to say hello. People know before the event if there's enough helpers to run the equipment. There's also the ability to create a forum for an event for newcomers to ask questions/general banter etc.
One interesting thing about meetup is that it doesn't have to be club based so long as someone can organise the yearly subs. So it could be an "ex uni/squad etc" group that meet only once a year for example.
I'm not working for meetup and there are probably other social networking sites of this ilk.

What do you think?