Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
ZCast - Live interactive podcasting with your Twitter followers
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Anchor.fm - Record bite-sized podcasts that anyone can join ⚓
Meetabit - All the local tech and startup meetups in one place - easy to organize & attend
X (Twitter) - Connect with your friends and other fascinating people. Get in-the-moment updates on the things that interest you. And watch events unfold, in real time, from every angle.