Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Konflist - Curated list of tech conferences all around the world!
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Event Hunt - Startups and Tech Events Curated By Locals
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
All Design Conferences - A list of all front-end and design conferences