Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Invitime - Meet new friends and challenge them to invite you
Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
RSVP Keeper - Online RSVP's made easy
Ticket Tribe - Sell tickets online with no fees per ticket
Guestboard - Lead powerfully-organized group events with Guestboard – a modular event platform that gives groups of 10-1000+ people a central space to coordinate, build excitement, and save money. No more crazy email threads. No more massive group texts.