Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Zoho Backstage - Plan, run, and analyze your event— all from one place
Cvent - Cvent's event management software provides event planners with a complete solution to increase event attendance and decrease event costs.
Meetup for iOS and Android - Discover groups that are all about the things you love
EventMobi - EventMobi is an interactive mobile event app, audience response and engagement platform for conferences and trade shows.