Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
CrowdCompass - CrowdCompass offers mobile app development for conferences, meetings, conventions.
Zoho Backstage - Plan, run, and analyze your event— all from one place
EventMobi - EventMobi is an interactive mobile event app, audience response and engagement platform for conferences and trade shows.
Meetup for iOS and Android - Discover groups that are all about the things you love
Attendify - Develop relationships at the events that you attend by creating smaller events with just a few people.