Shrink for Github - A macOS app for your Github issues
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
GitHub Reader - A quick way to browse GitHub issues and pull requests.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Codetree - You can manage your entire development process through GitHub.
Bigtent - BigTent is a web-based organization and communication portal for groups.