|An example of one such meetup|
Meetup is a type of social networking site designed to help groups of people with the same interests, well, meet up. On the site you can search for local groups by interest (such as Bollywood, board games, or bicycling), join the group, see when the next meetup is, and go if you wish. Or you can create your own group. It turns online networking into face-to-face connections; you join the group online, and meet up with them physically, which is interesting considering a lot of social networking sites aren't geared towards that physical aspect.
Personally, doing this kind of thing and going to a meetup would be way out of my comfort zone, but if I'm ever feeling particularly brave, I may give it a try. It seems like it would be valuable if you had just moved into an area and wanted to find and interact with a group of people with similar interests, or if you wanted to learn something new it would help you find people who could help you in a more informal group setting. Or you could go just to make new friends and have fun.