Openki - Platform where you can search, propose, take part, help organize or publish workshops, lectures...
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
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
SimCity BuildIt - Build, craft, and control! SimCity BuildIt is an all-new SimCity game designed just for mobile.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets