Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Citybound - Open-source city building sim with a focus on realism through microscopic details
Mobilizon - A free and federated tool to get our events off Facebook
SimCity BuildIt - Build, craft, and control! SimCity BuildIt is an all-new SimCity game designed just for mobile.
DownToMeet - DownToMeet is a platform to organize, find, and attend group events.
Get Together - Get Together is an open source event manager for local communities.