We are in Mensa. It's a great way to meet new people and make friends; each area usually has their own get-togethers and calendar of events.

http://www.mensa.org/national-groups

If you are in the US, you can search for the local chapter here:
http://www.us.mensa.org/AML/?LinkServID=85BA4820-E622-849E-15A997378678432D

Most of the chapters will have their own website and you should be able to see the calendar of events. At a minimum, there will be someone you can contact for more information.