Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Rocket Reads - A simpler alternative to Goodreads
Event Hunt - Startups and Tech Events Curated By Locals
Knowall - Book Recommendations from Friends
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Kooba - An interactive graph for finding new books