Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
WWDC app for OS X - An app to view and watch WWDC sessions on your Mac
Facebook Local - Discover places to go and events happening near you
WWDC Together - Watch and discuss WWDC together
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
WWDC for macOS Version - The best way to watch WWDC on the Mac