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

App in the Air - The perfect companion for everyone taking a flight.

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

Plip Trip Planner - Imagine having all of your travel arrangements organized in one, easy to read itinerary.

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

JetRadar - Compare flights from hundreds of airlines & travel agencies