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

Tix - Tix is a state-of-the-art, cloud-based ticketing system that features fully integrated access controls, event management controls, multi-channel distribution capabilities, and a robust reporting suite.

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

EventTitans - Top rated event management software

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

Brushfire - Brushfire offers tools for online registration and event management.