Raft Calendar - A fun and beautiful calendar for couples and close friends

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

Onin - Plan events without leaving the conversation

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

Ddays - Plan events with friends without the back and forth messages

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