Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Party with a Local - Party with a Local is a free app that connects travelers with locals that want to party.
Event Hunt - Startups and Tech Events Curated By Locals
Atmospheir - Fastest way to discover, connect and chat with your contacts
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Overnight - Book a last minute room with locals, in seconds.