Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.

Double - Tinder for double dates

Eventbrite - Discover Great Events or Create Your Own & Sell Tickets

Hater - The dating app that matches you based on what you hate

Bigtent - BigTent is a web-based organization and communication portal for groups.

Tinder - Tinder is how people meet. It's like real life, but better.