Meetup.com
Meetup isn’t so much of an online social network as an offline one. There are Meetup groups for almost anything you could possibly think of from groups for business networking, to new mothers, dog owners and co-ed indoor sport players. It also works in conjunction with Facebook, so you can check out which of your Facebook friends are also involved in Meetup groups. While Facebook is all about the people you know, Meetup is all about the people you don’t know, yet. Meetup allows users to try new things, meet new people and create new relationships.
