Abend - Every party starts with friends. The better FB events app.
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Elina - Elina is a web-based property management system designed to manage operations, profitability, and overall guess experience.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Charged newsletter - Weekly roundup of tech, boiled down into bite sized pieces
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.