Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Jukely - Go to hundreds of concerts for one monthly fee 💃
Event Hunt - Startups and Tech Events Curated By Locals
Sporteventus for iOS - The worldwide search engine for sporting events and tickets
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
TicketHarbor - The safer Craigslist for P2P ticket exchanges