Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Jason - Infinitely hackable mobile client
Facebook Local - Discover places to go and events happening near you
Kamon.io - Kamon makes an instrumentation library and Application Performance Monitoring tool that helps developers find and fix performance issues in microservices. Works best for Scala (Akka, Play, Lagom) and Java.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
WorkForce Software - WorkForce Software provides workforce management solutions for organizations with complex policies and compliance concerns.