WWDC Together - Watch and discuss WWDC together
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
WWDC TV - Watch WWDC video on your Apple TV
Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
NotesKey - Time travel through Apple's keynotes
pretix - pretix helps you to sell tickets for your event in an easy way. It supports multi-lingual events and provides a wide range of features