Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Klook - Discover & book amazing experiences at exclusive prices
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Party with a Local - Party with a Local is a free app that connects travelers with locals that want to party.
Meetabit - All the local tech and startup meetups in one place - easy to organize & attend
Overnight - Book a last minute room with locals, in seconds.