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