Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
PushPro - Send Push Notifications from any website to mobile devices
Facebook Local - Discover places to go and events happening near you
Push Notification Preview - A simple tool for previewing push notification copy
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Pusher - Pusher is a hosted API for quickly, easily and securely adding scalable realtime functionality via WebSockets to web and mobile apps.