Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.

Lurchr - Saves all your Slack links, so you can focus on work

Eventbrite - Discover Great Events or Create Your Own & Sell Tickets

Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.

Calendify - Calendify is an event community where you can share, publish, and subscribe to event calendars. It helps you to stay informed about what you are interested in and what is yet to come.

Slack News Feed - Get the top posts from every Slack chat you're in.