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

Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.

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

Eduflow - Digital learning that actually teaches students something

Bigtent - BigTent is a web-based organization and communication portal for groups.

Kialo - Kialo is the platform for rational debate. Empowering reason through friendly and open discussions.