Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Kommunity - Explore communities that share your passion with millions of people
Bylde - Bylde is a SaaS platform you can use to Start, Manage and Grow your groups and communities.
DownToMeet - DownToMeet is a platform to organize, find, and attend group events.
SportEasy - SportEasy is an awesome app to communicate with your team and organize your games and practices...
Get Together - Get Together is an open source event manager for local communities.