Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
NearGroup - Discover people via chatting, not swiping (Speed+Blind Date)
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Buzz Humble - Find someone on Bumble with Geo Location Search
Bigtent - BigTent is a web-based organization and communication portal for groups.
6People - Group chat with 5 new people every day in this mobile app.