Likewise - Get recommendations you love, from people you know.

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

Alternative Hunt - Learn about great alternative products as you browse the web

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

Pliim - One click and be ready to go up on stage and present!

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