(Thanks to NoCamels) This Israeli smartphone application allows you to connect with a group of your friends within a 1000-meter radius. For music events, parties, conferences or waiting for buses, trains or planes. Free for users, but businesses are charged to create events.
http://nocamels.com/2012/08/youhoo-app-to-create-location-based-communities/
http://youhooapp.com/