Huntathon - Browse and submit Product Hunt Global Hackathon projects
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Confs.tech - Open source list of tech conferences: JS / Ruby / Data etc.
Facebook Local - Discover places to go and events happening near you
CoFoundersLab - Meet 250,000+ entrepreneurs online
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets